NBC Dateline: Who is guilty in Diane Kyne murder case - husband or son?

The shocking murder of 49-year-old Florida woman Diane Kyne is the subject of NBC Dateline's upcoming episode that airs on Friday, July 29.

Kyne was found dead at her home with her husband Bill and her son Kevin present at the scene. The father and stepson provided conflicting testimonies that complicated the murder investigation. The official synopsis of the episode, titled True Lies, according to NBC News, states:

''When Diane Kyne is found dead in her bedroom, competing stories emerge about which of the two most important men in her life may have killed her. Dennis Murphy reports Friday, July 29 at 10/9c on NBC.''

Despite a detailed investigation and conviction, Diane Kyne's death remains a mystery. Read on to find out more details about the investigation.

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NBC Dateline: How did Diane Kyne die?

Diane Kyne reportedly died of strangulation or asphyxiation, according to the police. Her son Kevin Kyne made a frantic 911 call on a devastating afternoon in August 2010, saying his stepfather Bill murdered his mother and that he was trying to ''choke'' him. Kevin told authorities that his father told him his mother wanted to see him in the bedroom while the two were watching a race.

As he went there, he was attacked by Bill, and although he tried to scream for help in order to rescue his mother, he said she was already dead by then. Kevin went into detail, and according to Oxygen, described the moment he allegedly saw his mother in the bedroom:

''I saw my mom’s face. Her face was black and blue. It wasn’t even blue, it was just black and it was absolutely horrible...That’s a mental picture that’s going to be in the back of my mind for the rest of my life.''

However, what made things more complicated was that a few minutes after Kevin's panic-stricken emergency call, his stepfather Bill made another call, describing contrasting details of the same event. He said that his stepson killed his wife after he went to the bedroom in the midst of watching a race with him on TV. Bill said when he went to the bedroom to check in on his wife, he found Kevin on top of her, following which a scuffle ensued between the two. According to information obtained via Oxygen, Bill said,

''I hear her howl out ‘Kevin!’ in a loud voice and probably five, 10, 15 minutes goes by and so I get up to see what’s going on, I push the door open and I see Kevin on top of Diane.''

He further stated,

''I caught him at the kitchen, he was throwing me around like I was a rag doll...He shook me off again, took off for the door. He ripped the metal off of the door handle, pulling it off so hard.''

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NBC Dateline: Was Kevin Kyne or Bill Kyne convicted?

Police reportedly had strong reasons to suspect the two men, considering their history. Bill reportedly benefited from his ex-wife's life insurance policy after her death. Per Oxygen, he'd also purchased an insurance policy for Diane before her death. He also failed a lie detector test during the investigation.

Kevin, on the other hand, had his own tussle with the law. He had, previously, allegedly got involved in an intense argument with his aunt, following which authorities had to arrive at their house to arrest him. Bill also told the police about Kevin's allegedly violent behavior at home. In fact, Bill and Diane, according to Oxygen, at one point, sought legal help to get rid of Kevin from their house, but Diane later relented and allowed her son to stay in the house.

Authorities discovered Kevin's broken glasses below Diane's bed and found his blood on Diane's leg and the cover of her bed, following which he was arrested. Ultimately, Kevin was found guilty of murdering Diane Kyne and received a life sentence in 2012. A couple of years later, his conviction was overturned on appeal, and he eventually got out of prison.

In 2019, according to Oxygen, Bill was arrested on an unrelated case after he allegedly hit a team of cyclists with his motorcycle and left the accident scene. He was never convicted of killing his wife Diane Kyne. To this day, Kyne's murder remains a mystery.

Don't miss NBC Dateline: True Lies on Friday, July 29, 2022.