"She wanted money. She wanted the nice cars. But she didn't wanna work for 'em. She wanted it given to her. And she saw that with Dr. Stephens," says Keyes. "She started spending money at a clip after his death."
Stephanie was coping well with the grief of losing her husband. So well, in fact, that she married again a year later –- to a handyman named Chris Watts.
"In the month of June of 2002, when she remarried, she received an $80,000 annuity that they spent in four weeks," says Keyes.
Stephanie admits that her behavior was reckless, but she insists it actually shows how devastated she was that the love of her life was gone: "A bad decision. He was into drugs, milking me for money. I got myself tangled up into that by my own bad judgment."
And she says it was never about the money: "If I was so money hungry, it would have been much easier to just let him die from his illness, and inherit the money that way vs. trying to kill him. I mean, that just doesn't make any sense."
Stephanie also says she was so shocked when she found out how her husband died that she researched the drugs that killed him -- and the registered nurse found something investigators failed to consider. What she found out is that the amount of time it takes the drugs to work depends on how they're given.
48 Hours did some investigating of its own, and it turns out that Stephanie may be right. We asked Dr. Alan Lisbon, an anesthesiologist at Harvard Medical School and Boston's Deaconess Hospital, to show us how the drugs that killed Dr. Stephens work in surgery.
It takes 40 seconds to put a patient asleep if it's intravenously given. However, Lisbon says if it's given through an insulin pump under the skin, "the absorption of that drug would be much, much slower so that you wouldn't see effects of the drug for at least 5, 10, maybe even 15 minutes."
That means it would have been possible for David Stephens to give himself a lethal dose of these drugs through his insulin pump, and still have time to clean up afterwards.
In September 2002, 15 months after her husband died, Stephanie Stephens was arrested and charged with murder.
In a town rocked by scandal, Stephanie's lawyer, Ray Price, says his client is the victim of that hate. But prosecutor Keith Miller says her story can be summed up with another word – greed.
"One of the seven deadly sins. That got her," says Keyes.
More than two years after David Stephens' death, his young widow, Stephanie, is about to stand trial for murder.
Her parents and older daughter, Krystal, are trying to help her stay strong. But Prosecutor Keith Miller and Det. Rusty Keyes believe they can prove murder to a jury beyond a reasonable doubt.
"She's the only one that was with him for the 24 hours, the last 24 hours of his life, and he shows up with Atrucurium and Etomodate in his system," says Keyes.
For Stephens' daughter, Kristen, moving on means seeing justice served. "I'm nervous, but also a little bit relieved that soon it will be over and we can move on," she says.
Prosecutors begin by telling the jury that Stephanie's lust for money, her expertise as a nurse and behavior after her husband David died lay out like a roadmap to murder.
But defense lawyer Ray Price warns jurors not to be distracted by twists and turns in the road, and that the case is a witch hunt to frame Stephanie for killing her husband, when the doctor really killed himself. Price knows even the possibility of suicide could raise reasonable doubt with the jury.
After Keyes tells his story on the stand, Price goes on the offensive. He argues that Det. Keyes ignored medical records that showed how sick David Stephens really was -- and other leads that suggest he may have committed suicide. Price also tells Keyes that David was in therapy for depression, though his therapist declined to testify.
Prosecutors, however, are about to stun everyone in court. They say Stephanie actually admitted killing her husband and they have three witnesses to prove it.
The first witness is Karen Burnette, a friend of Stephanie and Chris Watts, who attended their Las Vegas wedding just a year after David Stephens died. It was there, Burnette says, when Stephanie told her that David said he wanted to die and asked his wife to help him.
"She told me that she injected him with two sedatives and a heart medication," says Burnette.
In defense, Price points out that Burnette should be on trial herself – for stealing items from Stephanie's house. It's a claim that Burnette denies, even though her house was robbed, and some of the stolen items were recovered from a storage locker registered to Burnette. Price thinks Burnette made a deal with the state to testify against Stephanie in return for immunity.
Burnette's husband, John, was also asked to testify – for being a witness in Stephanie's confession in Las Vegas. But he takes the Fifth Amendment.
And finally, the state wants Stephanie's current husband, Chris Watts, on the stand. But he's in jail, with troubles of his own.
Kristen Stephens has been waiting for two years to tell the court about the father she loved – and she wants to make sure the jury knows just how she lost him: "If someone were to tell me that my father committed suicide, I wouldn't believe it. It wasn't possible having known my father for that ever to be an option. I don't care what kind of evidence you have … My father would have never committed suicide."
But Price has a bombshell witness whose testimony might set Stephanie free – someone who claims that David Stephens was a classic suicide risk.
Dr. Gerald O'Brien, a psychologist brought in to review the case, says warning signs were everywhere: "He had a terminal illness. He also had a history of drinking regularly. The records indicate that his grandfather either attempted or committed suicide."
But what's most striking, O'Brien says, is the date David died: May 1, 2001 –six years to the day after his first wife, Karen's, funeral.
Now, Stephanie and her lawyer have to make a critical decision -- whether the jury should hear from her directly.
"I have nothing to hide and I think people want to hear my side of the story," says Stephanie. But she's acting strangely. She seems sedated. "I had such a rough night last night, not sleeping, with my leg hurting."
"She wanted to tell her story," says Price. "We just couldn't take the risk."
As the lawyers offer closing arguments, Stephanie can only watch and wait for her fate to be decided.
After only 90 minutes, the jury comes back with a verdict. The judge's words hit the courtroom like a shockwave: "Ms. Stephens, you have ended a life. The court hereby sentences you to life in prison."
Stephanie Stephens will not be eligible for parole for 30 years. "Never thought it would happen," says Stephanie. "No … I was honestly shocked. I told this before… I had not prepared for the worst. I had prepared, we had prepared to win."
She may have lost the trial, but she defiantly says she will never lose hope: "I've been pushed around and talked about and had all kinds of bad things said about me. It hurts, but I manage OK."
Although Kristen Stephens will never regain what she lost, she feels this just may be the next best thing: "Justice has been served … My mom and dad are here, and I just feel they were right here with me."
Stephanie Stephens says she's working on appealing her murder conviction. By the time she becomes eligible for parole in 30 years, she will be 65.
Since 48 Hours first brought you this story in January, Kristen Stephens has given birth to her second child -- a girl she named for her mother, Karen. You may recall that she named her son David in memory of her murdered father.
As for Kristen's stepmother, Stephanie, she's planning to appeal her murder conviction. As it now stands, by the time she comes up for parole in 40 years, Stephanie Stephens will be 65.