Who Killed Diane Kyne? Conviction, Appeal, and Retrial

No one has been held legally accountable for the killing of Diane Kyne. The question of who killed Diane Kyne has two possible answers and no confirmed one: her son, Kevin Kyne, and her husband, Bill Kyne, were the only other people in the Seminole, Florida home when she was strangled on August 15, 2010, and each called 911 to accuse the other. Kevin was convicted of second-degree murder in 2012, won a new trial on appeal, and was acquitted in 2015. Bill has never been charged.

The Night of the Killing

Diane Kyne, 49, was found face-up on her bed at the family’s 134th Street home in Seminole, dead from asphyxiation caused by strangulation or smothering.¹ Only her husband and her 23-year-old son were in the house.

Kevin called first. “Help me, please. He killed my mom,” he told the dispatcher, saying his stepfather had been choking him outside the house. Minutes later, Bill called with the opposite claim: “My son just killed my wife. He and my wife were arguing and he was choking her.”²

Lead homicide detective Jim Beining of the Pinellas County Sheriff’s Office later called it “a difficult case,” noting that both men “immediately accused each other as being the killer.”²

Two Stories That Don’t Match

Bill told investigators he heard Diane cry out “Kevin!” in a loud voice, pushed the bedroom door open, and found Kevin on top of her. He said he pulled his stepson off, was slammed into an armoire, and then chased Kevin through the house and into the yard.²

Kevin’s account was different in almost every particular. He said Bill told him his mother wanted to see him in the bedroom. When Kevin pushed the door open, he said, Bill grabbed him from behind and put him in a chokehold. Kevin insisted he never touched his mother and that Bill was the one who killed her.²

Both men gave statements that were inconsistent with the physical evidence, and each contradicted his own prior accounts as well as the other’s.³

The Physical Evidence Cut Both Ways

Some evidence pointed to Kevin. His broken eyeglasses were found at the foot of the bed, a sandal nearby, and drops of his blood were on Diane’s leg and on the bed cover. Prosecutors also drew on Kevin’s history of volatile behavior, including a 2005 arrest for battery on a law enforcement officer and Bill’s allegation that Kevin had once brandished a knife at his mother.²

Other evidence pointed to Bill. His DNA was found on a sample taken from Diane’s neck. He failed certain questions on a polygraph. And a deputy on scene noted that Diane’s body felt cold, suggesting she had been dead longer than Bill’s timeline would allow.² Bill attributed the DNA to the couple’s marriage. Florida’s Second District Court of Appeal later put the problem plainly: the physical evidence “did not definitively rule out either suspect as the perpetrator.”³

Kevin’s Conviction and the Appeal That Undid It

Police charged Kevin with first-degree murder.³ At trial in July 2012, prosecutors argued that Kevin strangled his mother after a fight over the family computer. Bill testified that Kevin had “attachment issues,” was reluctant to leave the house, and would badger Diane until he got his way.⁴ The trial judge allowed the state to present evidence of Kevin’s prior violent disputes with his stepfather, calling them “inextricably intertwined” with the events of the murder. The jury returned a verdict of second-degree murder, and Kevin was sentenced to life in prison.²

On July 11, 2014, the appellate court reversed. It held that admitting the prior-disputes evidence was an abuse of discretion, finding that “nothing about the evidence of Kevin and William’s prior violent disputes was necessary to adequately describe Diane’s murder or the context out of which it arose.” Because the case turned entirely on the credibility of two witnesses whose accounts contradicted each other and the physical evidence, the court concluded the error was not harmless and ordered a new trial.³

The Retrial: A Different Theory of the Case

The 2015 retrial before Pinellas-Pasco Circuit Judge Nancy Moate Ley focused on a theory the first jury had not heard developed in the same way: that Bill Kyne had killed his wife for insurance money. Assistant Public Defender Allison Miller told the court Bill had a “pattern of collecting insurance when bad things happen.”⁵

Bill held life insurance policies on Diane totaling roughly $750,000, naming himself as the beneficiary.⁵ He had also collected about $200,000 after the death of his first wife, Krista, who drowned in the swimming pool at the same Seminole home in April 2000 in an incident where foul play was not suspected.⁶ Beyond those, Bill had collected roughly $76,000 for a fire at his auto business around 2009–2010 and about $20,000 for a fire at an investment property.

Judge Ley limited how far the defense could take that argument. Jurors heard about the money Bill collected after Diane’s death but were not told about his other insurance claims or his failed polygraph.⁵ Miller also attacked Bill’s 911 call directly, telling the jury that “90 percent of what Bill Kyne said in that 911 call isn’t true.”¹ Assistant State Attorney William Loughery, for the prosecution, said prior investigations into Bill’s insurance claims had found no evidence of wrongdoing.

On February 10, 2015, the jury found Kevin not guilty. He was released the next day. Outside court, Kevin said: “There’s two people in the home — three people in the home, my mother being one of them that has died — and the other two, I’m innocent. There’s got to be a guilty party.”⁷

Why Bill Kyne Was Never Charged

The evidence investigators had against Bill — his DNA on Diane’s neck, the deputy’s observation that her body was already cold, the polygraph failures, the insurance policies — was never enough to bring a case. He was not arrested or charged in connection with Diane’s death. He denied any wrongdoing and continued to identify Kevin as the killer. He was later reported to have written a memoir, Love That Lasts a Lifetime, about the deaths of three wives.²

Bill’s only known arrest since was in May 2019, on an unrelated charge of leaving the scene of an accident with injury. Investigators said he had been “harassing the cyclists” on Gulf Boulevard and intentionally swerved his motorcycle into the bike lane, striking Dr. Lane Ziegler, who was hospitalized.⁸

Where the Case Stands

No one else has ever been charged in Diane Kyne’s death. Under double jeopardy, Kevin cannot be retried. Bill has never faced charges. The only two people in the house that night gave irreconcilable accounts, the physical evidence pointed at both, and the courts have produced one conviction that was thrown out and one acquittal. What actually happened in that Seminole bedroom on August 15, 2010, remains officially unresolved.²

1
Tampa Bay Times. Jury Gets Case of Seminole Man Accused of Murdering Mom as Defense Accuses
2
Oxygen. Diane Kyne Murder: Son Kevin Kyne and Husband Bill Kyne Blame Each Other
3
FindLaw. Kyne v. State, 148 So. 3d 1257
4
Spectrum News. Man on Trial for Mom
5
Tampa Bay Times. At Stepson’s Murder Trial, Man Questioned About Insurance Payments
6
Tampa Bay Times. Son Out of Jail After Slaying
7
Scripps News. Man Freed After Second Jury Acquits Him in Mother’s Murder
8
WFLA. Aggressive Motorcyclist Who Swerved Into Bike Lane on Gulf Blvd Arrested