In the fall of 2012, Lizzi Marriott was a new student at the University of New Hampshire, majoring in marine biology. She moved out of her home in Massachusetts that she shared with her parents, Bob and Melissa Marriott.

"She got into UNH," Melissa says of Lizzi. "She was on her way."

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Lizzi Marriott moved in with her aunt and uncle, Tony and Becki Hanna, in Chester, N.H, to save money on housing.

They remember how Lizzi quickly became a member of their immediate family.

"She'd scream, 'I'm home," says Becki, "And it really made us feel comfortable that she really felt like our home was also her home."

Video: Remembering Lizzi

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Lizzi Marriott was passionate about marine science, and volunteered at the New England Aquarium before heading to UNH. Her parents remember her always saving local wildlife.

"You'd see her and she'd have a tortoise in her hand or a little turtle," Melissa says about Lizzi, "and be putting it back on the brook side of our road."

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Lizzi Marriott's car was found in this parking lot in the UNH campus. The Marriott's would search tirelessly for their daughter, and received the help of friends, family and local and national police forces.

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Kat McDonough met Lizzi Marriott while working together at a local Target store in Greenland, N.H.

Lizzi had visited Kat's apartment once before, and agreed to come over again the night of Oct. 9 to watch a movie.

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Thanks to Lizzi Marriott's friends, police were able to find out early on that she was supposed to visit a new friend, Kat McDonough, on the night she disappeared.

Police were able to recover text message exchanges between Lizzi and Kat showing their conversation the night of October 9^, 2012.

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Kat McDonough shared an apartment with her boyfriend, Seth Mazzaglia, in Dover, N.H. The two were questioned separately by police on Oct. ^12, 2012.

Kat would tell police that Lizzi never came to the apartment that night, and stopped talking after about two hours.

Seth, on the other hand, spoke to police for 11 hours, and would say that Lizzi was at the apartment that night, and admitted that she died there.

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Seth Mazzaglia was arrested on Saturday October 13, 2012, and charged in the murder of Lizzi Marriott.

The news of Lizzi's death was devastating for her parents.

"I knew before I walked in that it was bad," Melissa says about hearing the news.

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A candlelight vigil was held for Lizzi on the night of Saturday, Oct. 13^.

Bob Marriott spoke to the crowd, and Lizzi's girlfriend, Brittany Atwood, left, also attended.

"Together we created an angel, and now she is home in heaven," Bob said to the crowd." Lizzi is a great tribute to everyone here, for that I thank you most of all."

Video: Lizzi Marriott's prophetic poem

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Nate McNeal was one of Lizzi Marriott's new friends in New Hampshire. He worked with her and Kat at the same Target store.

Nate remembers Lizzi's kind nature, and bright personality.

"Lizzi was like a ray of sunshine," Nate says. "She always had happy stories to tell people to brighten up their day."

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Nate McNeal was texting Lizzi Marriott on Oct. 9^, and made lunch plans with her for the next day. He became concerned when she stopped responding.

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During his 11 hour interview with police, Seth Mazzaglia went with detectives to Peirce Island in Portsmouth, N.H, where he told them he dumped Lizzi's body into the Piscataqua River--famous for its strong tides and currents.

The search for the missing UNH student now became a search for her body.

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Conrad and Perry McKinney are twin brothers who volunteered in the search for Lizzi Marriott's body.

Conrad, a private investigator, believes that Marriott's body may still be found. He and Perry still go out to search for her to this day.

"We'll keep searching," says Conrad. "It's probably going to be a long time searching, but that's what I do."

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The interior of the apartment Seth Mazzaglia and Kat McDonough shared.

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Lizzi's friend Nate McNeal reached out to Kat when Seth was arrested for Lizzi's murder.

"They never mentioned Kat," says Nate. "So I texted Kat and I said 'Please tell me you didn't know anything about this. And, she never texted back."

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Authorities searched the dumpster outside Seth Mazzaglia and Kat McDonough's apartment building. It is here that they would find some key pieces of evidence in the case against Mazzaglia.

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A trash bag found inside the dumpster contained evidence including Lizzi's sweatshirt.

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Also found in the dumpster were a pair of men's underwear, which was found to have both Mazzaglia and Marriott's DNA. Prosecutors would argue this DNA evidence supported their case for rape.

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On Oct. 17, 2012, Kat McDonough met with Seth Mazzaglia's defense attorney to go over her statement about the night Lizzi died--telling them she died in an accident.

Two months later on Christmas Eve, Kat is arrested for her involvement in Lizzi's death.

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Seth Mazzaglia's murder trial beganon May 28, 2014. On that day the court went on a site visit to Peirce Island, the location Mazzaglia told police he disposed of Lizzi's body.

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Kat McDonough, who originally came to Seth Mazzaglia's defense, has taken a deal to testify against him.

Kat now says that Seth murdered Lizzi the night of October 9, and that she helped him dispose of the body.

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The night Lizzi is killed, Seth Mazzaglia asks Kat McDonough to call his friend, Roberta Gerkin, who comes over to their apartment with her boyfriend, Paul Hickok.

Gerkin and Hickok would testify for the prosecution. To many jurors, their statements were among the most critical evidence in the case.

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Roberta Gerkin takes the witness stand on May 30^th, 2014. She said that as she walked into Mazzaglia and McDonough's apartment that night, she saw Lizzi Marriott on the floor.

"As I'm walking in there's a body on the floor," Gerkin says during testimony. "There's a body on the floor right next to the bed."

In U.N.H. murder case, why didn't witnesses call police?

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Roberta Gerkin also testified to seeing Kat McDonough in the fetal position in the kitchen of the apartment, and that Seth Mazzaglia was sitting on the bed next to Lizzi's head.

"He was sitting right there," says a juror. "Whereas Kat's in the fetal position in the kitchen, rocking ... That just told me right there he did it."

In U.N.H. murder case, why didn't witnesses call police?

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Paul Hickok, Roberta Gerkin's boyfriend, recalls being at Seth Mazzaglia and Kat McDonough's apartment the night Lizzi was murdered.

"All he kept repeating was 'he's gone too far this time, he's gone too far,'" Hickok testified.

In U.N.H. murder case, why didn't witnesses call police?

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Kathryn McDonough was on the stand for 10 days, and would paint a vivid picture of night Lizzi was murdered.

Prosecution would portray her as a young woman trapped in an abusive relationship, while the defense would try to paint her as a liar.

Video: Kat McDonough testifies

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A pair of gloves was also found by investigators, which Kat McDonough says Seth Mazzaglia put on before strangling Lizzi.

Some jury members found this to underscore the case for premeditated murder.

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On June 27, 2014, Seth Mazzaglia faces the jury's decision.

He is found guilty of first degree murder by strangulation, first degree rape and murder and two counts of conspiracy.

On Aug. 14, 2014, Mazzaglia is sentenced to life in prison without the possibility of parole.

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Even though their daughter's killer has been found guilty, her parents don't feel they can quite call it justice.

"Lizzi's dead, and she's not coming back," says Bob Marriott. "I think we got justice for other young girls and women."

And that, her parents say, is very important to them.

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The Marriotts have established a scholarship fund in Lizzi's honor.

The Lizzi Marriott Intrepid Explorer Fund gives financial assistance to "young adults looking to embrace an education and life working in marine sciences.

"I believe that the fund is the closest we can get to giving her a legacy," says Bob.

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