How This Georgia Man Almost Got Away With His Wife's Murder and Why Her Death Remains a Mystery

— -- On a warm summer night in a suburb of Atlanta, Georgia, a woman named Dominique Leili, known as Nique to family and friends, disappeared.

Her husband Matthew Leili claimed Nique intentionally left their home and their two young daughters behind.

But when her nude body was found in the nearby woods, suspicion turned to her husband, though how she died is still unclear.

Matt had installed 21 surveillance cameras around his family's home, and he used audio recorders to capture some of the fights he and his wife Leili had before she disappeared. It was later discovered that surveillance footage from the hours Nique Leili went missing was mysteriously deleted, according to police.

Nique Leili's family is convinced her husband is responsible for her death. "[I have] no idea what she saw in him," her sister, Amy Robinson, told "20/20."

A jury later found Matt Leili guilty of his wife’s murder, and Nique Leili's family believes justice was served, but her death is still a mystery.

Here's why:

June 28, 2011: Nique Leili Calls 911

Matt and Nique Leili lived with their daughters Amanda and Rebecca in Lawrenceville, Georgia.

Both 44, the couple was married for 13 years. But the two often fought over sex, money and Matt Leili's obsession with tracking her every move. Matt Leili, who worked in the security system business, installed 21 cameras throughout their house and spent much of his time watching the footage.

Their arguments were recorded on over 500,000 audio recordings, and it took investigators over a year and a half to listen to all of them. In one of the audio recordings, Nique said they were $300,000 in debt. Their marriage was crumbling, and the two were seeing a counselor.

Alex Peters, Nique Leili's daughter from a previous marriage, said she moved out at 16 years old because she didn't like Matt and the cameras made her uneasy.

"It was very uncomfortable all of the time, you know? He had a camera in the living [room] that faced the couch, so if you wanted to sit down and watch TV, you were being monitored," Alex Peters told ABC News' "20/20."

After Nique disappeared, Matt Leili would later insist to police that he installed the cameras in part because he was worried that his wife had become mentally unstable. Worried that she might run off in a rage and get hurt, Matt Leili told police he hid audio recorders in her purse and tracked her cell phone.

On June 28, 2011, Nique Leili called 911 saying her husband refused to let her leave the house. The police came, but took no other action. Later that day, Nique Leili grabbed an already packed bag and left.

Matt Leili then had their then-12-year-old daughter Amanda call Nique Leili to ask her to come home. Nique returned home that same day and things seemed to be getting back to normal – until two weeks later.

July 9, 2011: Nique Leili Disappears From Her Home

Nique Leili was last seen on the night of July 8, 2011, on the Leili surveillance cameras going out for a smoke before bed. The next day, she was gone.

Two days after she had disappeared, Matt Leili called Nique’s sister Amy Robinson.

"He said, 'Well, Nique's missing.' I said, 'What are you talking about?' And he said, 'Yeah, she hasn't been home since Saturday.' I said, 'Are you serious? Call the police,'" Nique Leili's sister Amy Robinson said. "And he said, 'No. I don't want to call the police.' And I said, 'Why?' And he said, 'Because then, you know, then we'll be on the news, and then she'll be so embarrassed that she won't ever want to come home.'"

July 11, 2011: Matt Leili Reports His Wife Missing to Police

After speaking to Nique Leili's sister Amy Robinson and father Doug Chatham, Matt Leili filed a missing person report. He told police that the night before she went missing, they had gone to dinner and a movie, but they got into an argument on the way home.

Matt Leili is heard saying in a recording of a phone call with police that they were talking about their sex life, "I said to her, 'Hey, how about you buying an outfit?' I think that might have set her off."

He said he and Nique had a fight and he had slept on the floor of his office. When he woke up the next morning, he told police his wife was gone, and the only thing she took was her toothbrush.

He also told police Nique had been breaking down mentally for some time and that she just walked away from their life, but Nique Leili's family said they resent what Matt Leili said about her mental condition.

"My mother was the farthest thing from crazy you could get," Peters said.

Before police even launched a search, Matt Leili hired a lawyer and filed for divorce on July 13, 2011.

"My reaction to that was, 'Who does that?'" Robinson said. "He wasn't worried at all about finding his wife. He was concerned about making sure that he spread the story that she was insane."

"It was just all about him. It was never a frantic, 'Where is my wife?'" said Peters.

Matt Leili also filled out paperwork at the courthouse to have Nique Leili committed.

July 16, 2011: Nique Leili's Body Is Found

Alex Peters helped organize a search of their own for Nique Leili and alerted the media, hoping to get the whole community involved.

More than 100 volunteers spread out through the neighborhood, but Matt Leili did not participate in the search.

Ten minutes after friends and family formed a grid, Nique Leili's body was found nude, covered in dead leaves and branches in the woods, less than a mile from her house.

"I heard somebody scream from the woods, you know, so I went running up there to see what they had uncovered. And it was my sister," Robinson recalled.

"I blacked out. I just remember hitting the ground," said Peters.

An autopsy revealed that Nique Leili died close to the time Matt Leili said she went missing and that there were high levels of GHB, the date rape drug, in her system. But the medical examiner was unable to determine how Nique Leili died. She was already decomposed and had no marks or signs of injury on her body.

In the investigation into Nique Leili's death, attention turned to the surveillance cameras at the family home. But in the hours she went missing, somehow none of the 21 cameras captured a single image.

Matt Leili told police he believed Nique may have pulled the plug for the cameras on her way out the door.

Though police suspected Matt Leili in his wife's murder, they determined there was not enough evidence to charge him at the time.

March 5, 2015: Matt Leili Is Arrested for Nique Leili's Murder

After his wife’s body was found, Matt Leili and their two daughters still living at home, Amanda and Rebecca skipped a memorial service for Nique and her funeral, and stopped talking to police.

On February 13, 2012, the day before what would have been Matt and Nique Leili's 14th anniversary, Matt and the two girls moved to Vermont.

In Georgia, Gwinnett County sergeant John Richer remained devoted to investigating Nique Leili’s murder. He ordered another review of Matt Leili's computer files using new technology that wasn’t available in 2011.

Gwinnett Police forensics detective Chris Ford found evidence that the security camera actually did record video from the precise hours when Nique Leili had left or been taken from the house, but someone had deleted it.

When Matt Leili came back to Georgia to testify in a civil lawsuit on March 5, 2015, over claiming money from Nique Leili's life insurance policy, police arrested him in the courthouse. He was later charged with murder.

Feb. 5, 2016: Matt Leili Is Found Guilty of Nique Leili's Murder

While awaiting trial, Matt Leili called his daughters Rebecca and Amanda from prison, which was recorded, and asked them to set up a YouTube channel to tell what he said was "the truth" about what happened in their home.

Rebecca and Amanda recorded YouTube videos defending their dad and attacking their mother's family.

"Honestly we can't wait to face this family in court and call out their lies and they've done nothing but cause us pain and torment and our day in court will come and hopefully my dad will be able to come home," Amanda is heard saying in one YouTube video.

At trial, prosecutor Lisa Jones presented the evidence that videos from the Leili surveillance cameras were deliberately and methodically deleted, beginning the very morning Nique Leili went missing.

The state's theory of what happened to Nique the night she disappeared is that when they got home from the movies on July 8, 2011, Matt Leili gave her some GHB to lower her resistance level. After they had sex, Matt Leili asphyxiated her by sitting on her or strangling her, according to Jones.

Joanne Lucie, Matt Leili's ex-wife before he had married Nique, testified that he got rough with her during their marriage.

"He would like to push you down to the ground, and pin you down. I'm not a very strong person, so I was easy to pin down," Lucie testified at trial.

Amanda, now 17, and Rebecca, now 14, also took the stand to defend their father. They testified that they never saw their father hit their mother.

Matt Leili didn't testify because he told the judge "I'm too emotional to testify."

In the jury room, jurors Kim Muenster and David Smith said that from the first juror vote, there was little doubt.

"I think one of the jurors said it best. He said, 'I wanna be able to go home tonight, and go to sleep, and sleep easy knowing that I did the right thing today,'" Smith told "20/20."

After three and a half hours of deliberation, the jury found Matt Leili guilty of malice murder and felony murder. The judge sentenced him to life in prison without the possibility of parole.

Today: Nique Leili's Family Believes Justice Was Served

Daughters Amanda and Rebecca, who are now in the care of Matt's father, have still not given up hope that their father will be exonerated, and Matt Leili plans to appeal his conviction. All three declined "20/20’s" requests for comment.

"He is falsely accused, pure and simple," Tom Clegg, Matt Leili's criminal defense attorney, told "20/20."

Nique Leili's family recently met with juror Kim Muenster and thanked her for helping bring justice for her murder.

Though her half-sisters believe their father is innocent, Alex Peters said she still loves them.

"As hard as this has been and as much, you know, hatred that they've harbored, my door is always open, because I don't blame them. I blame him. It's his fault," Peters said. "And so all I can do is just hope that they know that I love them dearly, and that I will always have open arms to them."