Produced by Asena Basak
Samira Watkins, a 25-year-old mother of a 4-year-old boy, was studying to be a dental assistant when she vanished. Five days after she disappeared, her body washed up in a duffel bag about 200 yards away from the entrance of the Pensacola Naval Air Station in Florida.
Working with the Pensacola Police Department, NCIS agents were able to link pieces of circumstantial evidence together to arrest Watkins' boyfriend at the time, Zachary Littleton, a Navy police officer. He was later convicted of murdering her and was sentenced to life in prison.
In his first TV interview, Littleton says investigators got it all wrong – and he admits he lied to them and was with Watkins the night she disappeared.
"I don't know what happened to Samira," Littleton says.
"They sentenced me to life in prison. Natural life. In the state of Florida, there's no parole – life is life," Littleton says. "I did not kill Samira Watkins."
Agents and investigators explain how they painstakingly and methodically tied the evidence together to solve Samira's murder and for the first time, Littleton explains what he says happened on the night he and Watkins were last together.
Pensacola Naval Air Station, home of the Blue Angels, is known as "The Cradle of Naval Aviation." More than 14,000 men and women from all branches of the military are based there. In the fall of 2009, NCIS played a key role -- teaming up with local police to help solve the murder of Samira Watkins, a beautiful young woman, with a promising future.
Alison Zavada | Deputy Assistant Director, NCIS: For NCIS, we investigate crimes committed against or by Navy … members … we're the fact-finders … that's our mission. … And we won't give up. We will pursue the truth.
Alison Zavada: Samira's young son, her family, they're without a mother, a sister, a daughter. That's who you really need to seek truth for.
Sylvia Watkins| Samira's sister [in tears]: It's hard.
Sylvia Watkins: She was always there for us whenever we needed her.
Alicia Cruz | Journalist: I don't think Samira's sister Sylvia has ever gotten over losing Samira. … her and Sylvia had a bond-- a deep bond. And that woman is literally heartbroken that she is never going to see her sister again.
Samira's tragic story caught the attention of New Jersey journalist Alicia Cruz, who, by chance, was in Florida on a different assignment.
Alicia Cruz: I just pretty much stumbled upon a story … And I worked on for … six or seven months after that.
Samira, the oldest of five siblings, grew up in a large, close-knit family.
Jasmine Robinson | Samira's cousin: Samira was a good role model for all of us, all her cousins, brothers, sisters. … And I looked up to her. … I still do.
April Joseph | Samira's sister: This is a picture of all of us at grandma's house.
Clarissa Joseph | Samira's cousin: We were always at my grandma's house.
April Joseph: I always say she was the favorite grandchild [laughs].
April Joseph: We was friends one day, enemies the next. We're sisters. That's what sisters do. … I'd describe her as the second mom. …It was a normal family. … Didn't have as much as other kids, but it was still fun.
Jasmine Robertson: Her dad had this jukebox. …And he used to … bring records to us … And it was one song called "Supersonic." We loved it. We used to dance off of it. We played it so much the record started skipping.
From early on, Samira was focused and hard-working.
Sylvia Watkins: She always had good grades. … she never missed a day of school. … she wanted to attend college.
When Samira got pregnant at the age of 20, she embraced motherhood.
Jasmine Robertson: Samira was … a great mom. … Her son … She loved him from the bottom of her heart. … She would do anything for him.
Alicia Cruz: Once she gave birth to her son, she decided that she wanted to take bigger steps in life. … She wanted a career, not a job.
The father of Samira's son was her first serious boyfriend, William Peters. But the young love became tumultuous.
Jasmine Robertson: He was … real jealous of Samira and he was just controlling. … I remember one time he … broke in the house and … stole from her … made it seem like it was somebody else, but it was really him … he was abusing drugs. … And it just got worse.
Alicia Cruz: He was extremely abusive, physically and psychologically abusive. … He kinda tore her down.
Alicia Cruz: By the time he had been arrested and convicted for the domestic violence, their relationship had spanned maybe three years.
April Joseph: We all felt free that that relationship was over. … Samira was ready for a fresh start.
Alicia Cruz: This was a young woman with a big heart. … She was starting her life over. And him going to prison gave her a new lease on life.
With that burden behind her, Samira blossomed.
Alicia Cruz: She got a job at a restaurant where, within six months, she was an assistant manager. … She was going to school to be a dental assistant. So, she had gotten herself together.
And there'd soon be a new man in her life: a sailor she met while visiting the Pensacola Naval Air Station.
Zach Littleton | Former Master at Arms, NAS Pensacola: I was working the main gate at NAS Pensacola. And she approached the gate in her vehicle … And I asked to see her ID.
Zach Littleton: She came off as friendly. … She had a nice sex appeal about her. A nice smile, you know … She seemed like she took care of herself.
Alicia Cruz: And he asks her her name. And she tells him it's Samira. And … he said…. "my name is Ricky."
Alicia Cruz: And they agreed that, you know, they're gonna go out Saturday night … and she couldn't stop talking about him … just how every woman does when she meets that guy, the butterflies and the excitement.
Ricky Littleton was a member of the security forces on Pensacola Naval Air Station.
Zach Littleton: To know that you are out there serving a purpose for the greater good of the whole nation is an awesome feeling.
Alison Zavada: He was assigned as Master at Arms duties … They're the military police … that enforce the rules and regulations … on base.
Alicia Cruz: She must have thought, you know, this is just icing on the cake. … She had just come out of a very damaging relationship. She wanted better for her son and for herself.
April Joseph: I was happy that she met Ricky. I mean, we're from a military town so every girl knows you get a military guy.
Their summer romance lingered into fall.
April Joseph: … we kind of felt like it was getting serious because … we wouldn't see her at home as much.
Alicia Cruz: … she's finally found someone she feels safe with that, you know, treats her very well. … she felt that the relationship was, you know, stable. And they were gonna go further.
Their relationship would soon arrive at a significant milestone.
Alicia Cruz: She thought she was pregnant. And she took a home pregnancy test and found out she was.
April Joseph: To me … he almost looked like a dream come true.
Jasmine Robinson: It was a happy moment. … She wanted a bigger family. … But she wanted it with the right person.
Alicia Cruz: She felt blessed. That's what she had written on her MySpace account. And, you know, life was good.
But just a few weeks later:
911 OPERATOR: 911, Where's your emergency?
SYLVIA WATKINS: I would like to report a missing person.
911 OPERATOR: Who is she?
SYLVIA WATKINS: It's my sister.
911 OPERATOR: And what is her name?
SYLVIA WATKINS: Samira Watkins.
In the fall of 2009, pregnant and in love, Samira Watkins was on top of the world.
Alicia Cruz: She met this handsome, seemingly kind, loving, young sailor. And she thought … "my prayers have been answered."
Then, on October 29. It all changed when she vanished.
Sgt. Jonathan Thacker | Pensacola Police Dept: When I received the call … the officer told me that the young lady that was missing … was pregnant and was pregnant by a gentleman who was in the Navy.
Detective Thacker soon learned that not everyone was happy about Samira's pregnancy -- especially her boyfriend Ricky.
Alicia Cruz: … up until that moment, there had been no signs of trouble in that relationship. … But once she told him she was pregnant, it all went downhill.
Sylvia Watkins: He was more like in shock, like he couldn't believe what just happened.
Alison Zavada: She wanted him to provide some financial support and he wanted her to have an abortion. … But she was dead set against that.
Zach Littleton: I wanted her to do what's best for her because she already had a child. … I never said, "I want you to have an abortion." It was just a discussion we had.
But Samira's family says Ricky grew distant after finding out about the pregnancy.
April Joseph: I think she just started to get nervous about Ricky … so I think she just started to get suspicious.
With the help of a friend in the military, Samira discovered Ricky was leading a double life.
April Joseph: She found out … Ricky wasn't his real name and also that Ricky was married.
Sylvia Watkins: His real name was Zachary Littleton.
April Joseph: I just remember her being upset … and confused.
Not only was Littleton married, he also had a young daughter. Jasmine says he told Samira his marriage was on the rocks.
Jasmine Robinson: … I think he probably lied to her and told her that him and his wife was going to divorce.
Jasmine Robinson: … that's when … she started having doubts.
The couple grew apart. After some time, Samira's family says Littleton reached out. And by late October, she seemed hopeful.
Jasmine Robinson: He said that he wanted to make things work with them … for the baby's sake.
Alison Zavada: Samira had received a phone call from Zachary Littleton earlier in the night of the 29th and said that he wanted to talk to her. … So, after work, she went from her house to his apartment … and then she was never heard from again.
The next day, when Samira didn't return home, Sylvia and Jasmine drove to Littleton's apartment.
Sylvia Watkins: We knocked on the door. We banged on the windows. … A lady came out saying that he moved out. He just all of a sudden up and moved out.
That was when Detective Thacker got the case and learned about Littleton's two identities.
Sgt. Jonathan Thacker: My first thought was that this must be a misunderstanding. He's a police officer. … he'll probably explain this.
Sgt. Jonathan Thacker: Sylvia … was using two different names for Littleton. One name was Ricky and one name was Zach … I wasn't really sure what his name was.
[PHONE CALL AUDIO]
SGT. JONATHAN THACKER: Hey, how you doing? Is this Ricky?
ZACH LITTLETON: This is uh, Zachary Littleton.
THACKER: This -- Oh, OK.
Sgt. Jonathan Thacker: That was certainly interesting … But it wasn't necessary cause for thinking that he had done something to her.
[PHONE CALL AUDIO]
SGT. JONATHAN THACKER: Hey, do you know this young lady Samira?
ZACH LITTLETON: Samira. Samira. Yeah, she said Sammy, that's what she told me to call her, Sammy.
SGT. JONATHAN THACKER: Do you know where she is now?
ZACH LITTLETON: No, I don't.
SGT. JONATHAN THACKER: OK. Alright, look, here is the deal, she has been reported missing, OK? And I need to talk to you, and not over the phone.
Two days after Samira's disappearance, Detective Thacker brought Littleton in for questioning:
SGT. JONATHAN THACKER: Did you have any kind of a relationship with Sammy that was more than just friends?
ZACH LITTLETON: No ... It was just friends. That's what I thought it was.
Sgt. Jonathan Thacker: Littleton was slow to admit to me the full extent of he and Samira's relationship.
Sgt. Jonathan Thacker: He did tell me he is married to another woman -- that he had his own child with the wife.
Alison Zavada: Zachary Littleton was a geo-bachelor from his wife for a good amount of time. … That means basically … that somebody is living away from their family.
Alison Zavada: His wife was in the military … as well and she was located in South Carolina.
Sgt. Jonathan Thacker: The military has very strict rules about infidelity … And he was potentially going to be punished by the Navy for having an affair outside of his marriage.
Mark Gustashaw: Zach was very devout … to his family to his wife and kid.
Mark Gustashaw: But I knew for a fact … Zach … had a second life.
Mark Gustashaw was a friend of Zach's and worked with him on base.
Mark Gustashaw: Ricky was the name that he would go by out in town.
Alison Zavada: He … was known as a playboy around base. … In fact, he had been investigated by his command for having … an adulterous affair.
Zach Littleton: To say I had two personas … It's not true. … At the age I did get married, it was a lot of things I hadn't experienced.
Zach Littleton: To be honest … Samira wasn't the only girl I was havin' an affair with.
Sgt. Jonathan Thacker: I tried to help him open up.
SGT. JONATHAN THACKER: I want you to know that I'm not the military. I want you to feel free to tell me everything without being worried about getting in trouble.
ZACH LITTLETON: OK, we had sex once or twice.
Littleton told the detective he was no longer seeing Samira because his wife was transferring to Pensacola Naval Air Station in less than a week.
Alison Zavada: His wife and child were scheduled to move to Pensacola … so he had already set up a larger place on the other side of town.
Sgt. Jonathan Thacker: So, of course, one of the main questions I wanted to ask Littleton … was where he was at on the night of the 29th.
That was the night Samira went to see Zach … and the night she went missing.
Sgt. Jonathan Thacker: His answer … was … He was moving out of that apartment the next day. … And, so he was at home all night packing.
ZACH LITTLETON [interrogation]: Thursday I was at home, and she didn't come over.
Sgt. Jonathan Thacker: He says she never showed up.
Meanwhile, Samira's 4-year-old son started asking questions.
Sylvia Watkins: He was asking where his momma was.
Three days into the investigation Thacker was convinced Littleton was not forthcoming, so he had him come in a second time.
Littleton once again denied any involvement in Samira's disappearance:
SGT. JONATHAN THACKER: What do you think happened with her?
ZACH LITTLETON: I hope she's OK. I don't know what to think.
SGT. JONATHAN THACKER: You need to! You need to.
ZACH LITTLETON: I need to?
SGT. JONATHAN THACKER: Yeah.
ZACH LITTLETON: Y'all feel like I had the motive to do something to her, but really, I didn't do nothing to that girl. I don't even know where she is.
Investigators processed Littleton's apartment and car for evidence.
Sgt. Jonathan Thacker: There was no sign of blood in the apartment … or anything that would make it … clear that some foul play had occurred.
But their search for Samira Watkins in the police database would turn this case upside down.
Sgt. Jonathan Thacker: That search led us to realize that Samira had been a victim on a few different occasions of domestic violence, batteries … by the father of her child William Peters.
Prosecutor Bridgette Jensen got involved with Samira's case early on.
Bridgette Jensen | Assistant State Attorney, Escambia County, Florida: The prosecution is alerted because it's under suspicious circumstances. … Will Peters and Samira did have a violent past … he's certainly someone that needs to be looked at.
Sgt. Jonathan Thacker: What I found was a total of five different reports … The one that actually got him sent to prison was … he battered Samira and their child and would not allow her to leave the house … The charges were false imprisonment and two counts of simple battery.
Prosecutor Bridgette Jensen: He had been released from prison at the time Samira went missing, and she also had … a restraining order against him at the time.
Sgt. Jonathan Thacker: Prior to finding out about him, Littleton was looking like he would be the prime suspect.
Sgt. Jonathan Thacker: Now we find out that there is this other individual that could be involved … We are open to anything at this point.
For four days, Samira Watkins' whereabouts remained a mystery. But all that would change when two jet skiers found a duffel bag washed up on shore near Pensacola Naval Air Station.
Alison Zavada | Deputy Assistant Director, NCIS: …we were just looking anywhere on base … I just recall vividly … standing on the bridge and looking over, and there was a lot of police activity. And that was where she was found.
Sgt. Jonathan Thacker: This is exactly the spot … just about 30 feet in front of me in that sandy area on the shore.
Alison Zavada: Samira's body was … probably 200 yards or so away from where the naval base starts.
Sgt. Jonathan Thacker: We had Samira's fingerprints already ready. … So right there on the scene a comparison was made and it was positive that, that was Samira's body in that bag.
NEWS REPORT: Police finally confirmed it was the missing Pensacola woman they had been searching for.
Zach Littleton: I seen it come across the news … that they had found a body. … it's a whole 'nother world. It's a whole 'nother issue now.
Littleton says he was stunned.
Zach Littleton: I didn't think she was missin' at all. I think she was just pullin' a stunt to get my attention. … I felt like I'm in the middle of a beehive that I don't know how to get out of.
Sgt. Jonathan Thacker: Samira … was inside the bag in the fetal position. She had multiple layers of duct tape wrapped around her head and it went up over her nose.
Alison Zavada: The medical examiner determined that Samira's cause of death was asphyxiation.
Sgt. Jonathan Thacker: Law enforcement officers … we get very mechanical. … you forget sometimes about these families. … Around the same time my wife was pregnant. So, it made it even more real to me.
On November 10, Samira was laid to rest.
April Jackson: I actually didn't really feel it or feel that she was missing … until I seen her casket. … it was our home church … it was like, once the doors flew open, it was just like this is it … This is real.
Sylvia Watkins [in tears]: So, at the ceremony … I know my daddy he couldn't leave her side. He had his hand on her casket.
Sgt. Jonathan Thacker: Certainly, watching the heartbreak and the emotions … remembering that Samira still has a son … he's done with seeing his mother, it's never going to happen again. … I really wanted to see this one all the way through.
Solving this case would require old-school detective work. Many of the forensic clues had washed away.
Prosecutor Bridgette Jensen: Any sort of DNA is going to be difficult to obtain from something that's been in the water for five days.
But there was physical evidence.
Alison Zavada: When the contents of the bag were examined, in addition to her body, there was a paper towel and a couple of … disinfectant wipes.
Sgt. Jonathan Thacker: … seemingly the killer used them and tossed them in the bag to get rid of them along with Samira's body.
One of the first suspects investigators looked into was Samira's ex-boyfriend William Peters, who had served time for beating her and their young son and holding them against their will.
Sgt. Jonathan Thacker: William Peters told me that since he'd gotten out of prison he was working with his family members. They have a cleaning service. … I didn't see any of those supplies at his house. … I was able to find out that he was on a job at the time that Samira went missing.
Sgt. Jonathan Thacker: So, his alibi checked out about as well as it could. I mean, it wasn't perfect.
Sgt. Jonathan Thacker: …despite the fact that William … had harmed Samira in the past. He actually seemed very upset.
Hunting for clues, investigators combed through Samira's cell phone records.
Sgt. Jonathan Thacker: I'm seeing this one number that's continually calling her. … it's also a number that she's been calling daily since around October 20th. … So, obviously, I want to know … who it belongs to. … By all accounts it doesn't belong to Littleton because he gave me his numbers.
Remember, Littleton had also told investigators he was no longer in touch with Samira and that the affair was over.
Sgt. Jonathan Thacker: So, there was a total of 47 calls made between Samira and this … number from October 20th until October 29th. Eleven of those calls actually occurred on October 29th, the last day that she's ever seen.
Detective Thacker soon tracked this mystery number to a "toss phone" and he didn't have to look far for its owner.
Zach Littleton: I didn't think nothing … was wrong with me having an extra phone.
Sgt. Jonathan Thacker: He's calling her still … they're talking actually more frequently at the end of her time than they were at the beginning.
He was now their prime suspect.
Prosecutor Bridgette Jensen: We know that Samira was on her way to see him the night that she went missing. We knew that she was pregnant. We knew that Zachary Littleton was obviously not happy about the pregnancy.
Alison Zavada: It's a big deal that he was the prime suspect in this murder … because … he had been entrusted with carrying a weapon and carrying out the duties of a law enforcement officer on base.
Zach Littleton: I probably was their only suspect … I just felt like all eyes was on me.
NCIS and Pensacola P.D. interviewed Littleton's colleagues and friends in the Navy:
SGT. JONATHAN THACKER: What was his demeanor like?
FRIEND OF ZACH LITTLETON: He was just real, like… any other normal person, just quiet. … He's a good person, I really don't think he has anything to do with it. I really don't.
Alicia Cruz: Other sailors that worked with him … they could not believe he had done anything, especially on the night police said he had because they saw him the following morning. And he was in good spirits … And they said he was just his normal self.
Mark Gustashaw: I wanted Zach to be free as much as I wanted the killer to be found -- you know, I wanted his name to be cleared.
But Mark Gustashaw was the one friend who led investigators to question Littleton's alibi.
Mark Gustashaw: Zachary called me and … said … "Can you help me move tomorrow morning."
Alison Zavada: As part of Zachary Littleton's alibi, he had claimed that he was up all-night packing for his move.
Mark Gustashaw: He assured me everything would be packed and ready to go and boxed up and it could not been further from the truth. … There was literally nothing packed. You walked in the apartment and even his clothes were still on the dresser. His food was still in the fridge.
Samira's autopsy revealed another piece of the puzzle.
Alison Zavada: So, there was a gold hoop earring missing.
Prosecutor Bridgette Jensen: They had some sentimental value to her, so she always had these earrings on. … She only had one of those earrings.
Alison Zavada: On the day that she disappeared, Samira … wore both earrings to work … So, this earring had to have come off of her at some point between her disappearance and her body being found.
Sgt. Jonathan Thacker: … you find a body. It's got one earring. It's missing the other one. You want to find the other earring. It's huge.
THE NEEDLE IN A HAYSTACK
On November 4, just a day after Samira's body was recovered, Littleton's neighbors came forward with an important clue about a couple arguing in the parking lot on the night of Samira's disappearance.
Sgt. Jonathan Thacker: The female was up against what they describe as a red vehicle, which is consistent with Samira Watkins' red Ford Taurus. … They remember hearing the female telling the male to calm down.
Next day, a resident spotted Samira's red Taurus at the driveway of a vacant property almost 10 miles from Littleton's apartment.
Sgt. Jonathan Thacker: Then her glove box was a letter from her doctor. The letter basically congratulated her on being pregnant.
On November 6, investigators searched Zach Littleton's new house, as he looked on.
Sgt. Jonathan Thacker: I just remember him being very nervous.
Sgt. Jonathan Thacker: There was a number of things that we were looking for. I'd say tops on our list was the earring. … sure enough during the search one of our detectives located that matching earring … in one of those plastic comforter bags.
It was a game changer.
Sgt. Jonathan Thacker: … that earring was sitting there in that bag … it matched in appearance exactly to the earring that Samira was missing.
Sgt. Jonathan Thacker: He made a spontaneous statement when that earring was shown to him that "that's my wife's" which none of us believed.
And there was more: the discovery of paper towels.
Sgt. Jonathan Thacker: … the design … was like a purple or bluish looking bird and some kind of flowers.
The same pattern from the paper towel which was found in the duffle bag with Samira's body. In addition to those …
Sgt. Jonathan Thacker: … we found tubs of Clorox wipes, consistent with the wipes that were found inside the bag.
At that point, Littleton shut down.
Sgt. Jonathan Thacker: He made it very clear he would not be speaking to us.
He was adamant investigators had the wrong man.
The case was still largely circumstantial. So NCIS, for the first time in its history, mapped cell tower data to track Samira and Zach's movements on the night she went missing.
Sgt. Jonathan Thacker: NCIS was very quick to let me know that they had technology that we didn't have here at that time … for the mapping of cell towers.
Alison Zavada: In 2009, there was no GPS data. … NCIS has some unique capabilities … We have resources that we can reach back to at our headquarters.
Alison Zavada: The analysts were able to … track all of the movements of Samira Watkins and Zachary Littleton on the night of her disappearance.
Christine LaBounty | Analyst, NCIS: We were attempting to … develop a timeline based on those calls. …the blue markers are Littleton's movements, and the orange markers are Samira's. … Zach Littleton was on base, finishing up work … And Samira was … in that general region around the same time.
Christine LaBounty: At 22:14, Littleton made a phone call to Samira. … we can also see that both Samira and Littleton are moving towards his apartment up here in the vicinity of point D.
Sgt. Jonathan Thacker: So, over my right shoulder, you'll see a cell tower that Samira Watkins' last call hit off of, maybe a quarter mile from Zachary Littleton's apartment.
Christine LaBounty: Samira's final call … was at 22:37 … And that call was to Zack Littleton's toss phone. And it's in the vicinity of his apartment.
According to NCIS analysis, Littleton was on the road in the early morning hours of Samira's disappearance. He missed call from a Navy friend at 4:36 a.m.
Christine LaBounty: … at 4:37, Littleton called back. And as you can see from this map, Littleton … was moving back towards his apartment at 4:37. … So, this map contradicts Littleton's statement that he made to police that he was home all-night packing. It clearly shows that he was not at his apartment and was returning back … around the 4:30 hour.
Police theorized it was Littleton who had dumped Samira's car. But how did he get back to his apartment? They thought he might have used a taxi, so they searched dozens of taxi pick up receipts and their hunch paid off.
Sgt. Jonathan Thacker: The name on that taxi record was Zach.
The call was made about half a mile from Samira's car from a Waffle House at 4:20 a.m. That's where investigators headed next.
Sgt. Jonathan Thacker: Luckily, they still had the video footage of this individual entering Waffle House asking to use the phone. And when I saw that video it was Zachary Littleton. No question about it. In fact, in one frame he looks up at the security camera you see a clear picture of his face. It was definitely him.
Sgt. Jonathan Thacker: And it was almost like that deer in headlights look.
Sgt. Jonathan Thacker: Not only that, but he's carrying with him a tub of Clorox wipes. Consistent with the same wipes that we had found in the bag. … The kind of thing that you would expect somebody cleaning up a crime scene to have.
Sgt. Jonathan Thacker: That was one of the moments I'll never forget … when I saw him at four in the morning in a place that he wasn't supposed to be within a half a mile of Samira's car, that's when … I felt very confident that we were going to be able to make an arrest on this.
Three weeks after Samira's body was found just few hundred yards away from the front gate of the Pensacola Naval Air Station, investigators moved in to arrest Littleton.
Sgt. Jonathan Thacker: They had pulled Littleton into a room. … and I informed him that we were there to arrest him for murder.
Zach Littleton never gave another interview to investigators, but when he did speak with CBS News almost 10 years after Samira's murder -- he had a different story to tell.
Zachary Littleton: That night … I told the police I was at home all night packing … I was with Samira in truth.
THE SMOKING GUN
Zachary Littleton: I know I'm innocent. …I know there's a God. I know he's a miracle worker.
On June 27, 2011, almost two years after Samira's body was found, Zachary Littleton went on trial for her murder.
Sylvia Watkins: I wanted justice for my sister.
Prosecutor Bridgette Jensen: He was not charged with the death of the baby. … Florida statutes require there to be a viable fetus, and Samira's baby was not that far along. Samira's family -- and the prosecutor -- worried there was no hard evidence linking Littleton to the murder.
April Joseph: I was nervous during trial. … I just didn't want him to be able to get away.
Prosecutor Bridgette Jensen: The case was circumstantial … There was no confession. There was no really, any direct evidence.
Littleton appeared almost cocky during the trial. He never took the stand.
Prosecutor Bridgette Jensen: Zachary Littleton's demeanor … was confident, maybe on the edge of arrogant.
Jasmine Robinson: He kept a little grin on his face the whole time … he never showed no fear. None of that.
But NCIS' cell tower analysis and Littleton's lies would catch up with him.
Prosecutor Bridgette Jensen: NCIS's work on the cell tower information helped destroy Zachary Littleton's alibi.
At the trial, Prosecutor Jensen presented more incriminating evidence found on Littleton's computer.
Prosecutor Bridgette Jensen: At the end of September … there were some searches on Zachary Littleton's computer for things like abortion clinics.
Prosecutor Bridgette Jensen: On the day Samira went missing, Zachary Littleton was actually doing searches on the Internet for … how to speed up human decomposition.
Alison Zavada: He was feeling boxed in -- in terms of what do I do with my girlfriend that's pregnant and my wife coming.
Littleton says the investigators got it all wrong.
For the first time, he's telling CBS News his version of the events.
He says he lied about being at his apartment packing up the night of the murder.
Zachary Littleton: I told them that because I didn't want to have anything to do with their investigation.
He now admits he was with Samira that night.
Zachary Littleton: We talked and we, you know, we had sex … And I told her … you can spend the night. … But this is probably, you know, ain't gonna happen no more. We're not gonna be intimate like this anymore.
Zachary Littleton: We didn't have to argue, we didn't have to fight. She knew that my wife was coming.
Zachary Littleton: … after we hung out for a few hours, she decided, "You know, we should go get something to eat." … I said, "Where you wanna go this time of night?" She said, "Waffle House open 24 hours."
During that drive, he says the conversation became heated.
Zachary Littleton: She became angry, and stopped the car, and asked me … What is it about her I don't like? … she told me to get out her car.
And he tells CBS News that was the last time he saw her.
Zachary Littleton: I don't know what happened to Samira.
Investigators say that's pure fiction: they agree Samira was in Zach's apartment the night she disappeared -- and that's when he killed her.
Alison Zavada: … he really changed his tune … with Samira about having the baby … that had to have been … some type of lure … to get her to the apartment.
Sgt. Jonathan Thacker: … at some point, Zachary, I believe, grabbed Samira by her neck … he strangled her … to make sure she was … dead … So he took the duct tape, wrapped it very thick around her mouth, her nose and he put her into a duffel bag.
Sgt. Jonathan Thacker: He walked it out to Samira's car, put her in the trunk … He drove down the bridge. … it's three, four in the morning. Nobody's really around. He … threw her into the water. … And he found a place to dump the vehicle here in Pensacola.
At the trial, jurors watched that surveillance footage from the Waffle House where Littleton was seen carrying a container of cleaning wipes.
Zachary Littleton: The reason I had … the cleaning wipes was 'cause … I had an abundance of cleaning stuff … first thing you move into a house, you want to clean. … And she took one, talking about how she needed some. … But when she put me out, she threw 'em at me. And I picked 'em up. "OK, you don't need 'em? I'll take 'em."
But Prosecutor Jensen says there was more damning evidence: one of Samira's prized possessions tied Littleton directly to her murder.
Prosecutor Bridgette Jensen: The closest thing to a smoking gun in this case … were the earrings.
Littleton says he has no idea how Samira's earring ended up in his new house.
Prosecutor Bridgette Jensen: … this earring, to my left, was actually located … at Zachary Littleton's house. … And we were able determine that had Samira Watkins's DNA on it. … The clasp on this particular earring is … broken. … that … enabled the state to argue that there was some sort of struggle in Zachary Littleton's apartment.
On June 30, 2011, after a three-day trial, the jury began its deliberations.
Sgt. Jonathan Thacker: This homicide was one of my first homicides that I ever worked and so … I already had a certain level of nervousness.
It took the jurors just three hours to reach a verdict: guilty of first-degree premeditated murder.
Jasmine Robinson: I was happy when they said he was guilty. … it brought back … joy in my heart.
April Joseph: I knew I was going to hear a guilty verdict. But … It just felt like she died all over again after the verdict was read guilty. It's the end.
Zachary Littleton: They sentenced me to life in prison. Natural life. … In the state of Florida there's no parole. … life is life.
Zachary Littleton: I did not kill Samira Watkins.
April Joseph: If I had to say something to him … I pray that you be able to get the healing and help that you need … and hope one day that you will be able to come to terms for what you've done.
Jasmine Robinson: I don't care how many years go by. … I still remember her. Clear as day.
Alison Zavada: When you kind of reflect … you see the human aspect of it.
Alison Zavada: I got kind of chills thinking about it. … as a mother … what really came together for me … Samira paid the ultimate price for protecting her child.
Alison Zavada: You need the humanity in all of us. … there needs to be a resolution. … because you can't have crimes like this go unpunished.