High School Sweetheart Turns Femme Fatale: Businessman Brutally Gunned Down By Ex-Wife

When authorities first responded to a shooting at the Horwitz household in Jupiter, Florida, on Sept. 30, 2011, their first inclination was that Lanny Horwitz, the man slumped over dead in the bathroom, had committed suicide. After all, one of the people present, Lanny’s ex-wife Donna Horwitz, was reportedly repeating, “He’s so mean…He’s been saying he would do this,” while claiming to not be able to hear what anybody was saying when security guards arrived; their son, Radley, simply said he had heard gunfire.

But given the number of shots fired, the position of the bullet holes and the fact that there was an empty five-shot revolver found next to the victim, that theory quickly went out the window.

“I told everybody, ‘Stop right where you are — this is not a suicide,’” Eric Frank, a detective with the Jupiter Police Department, said in the latest episode of Oxygen’s true crime anthology series, “In Ice Cold Blood.”

Thus began the process of unraveling the drama surrounding the Horwitz family, and how Lanny ended up being shot nine times, including once in the mouth.

Lanny Horwitz was a once successful real estate mogul who had a tumultuous, on-again, off-again relationship with Donna. According to family members interviewed for the episode, Donna had swept Lanny off his feet in their younger years. But throughout their marriage, she would prove to be unfaithful on multiple occasions, though Lanny always wound up taking her back, at least at first.

Donna and Lannyy Horwitz Photo: Jill Mack

“That was a pattern,” Lanny’s cousin, Linda Freeman, said in the episode. “When she ran out of money, she came back to Lanny.”

The couple was married and divorced twice over the years. At the time of the murder, the two, along with their son, were living in the same home, although Donna and Lanny seemed to have different ideas of what the reunion ultimately meant.

As Donna wrote in her diary, she was first ecstatic about the arrangement, and felt like it could be a new beginning for them. But, later on, her feelings soured as she realized that Lanny only seemed concerned about the $200,000 she loaned him: Donna repeatedly referred to him as “Mr. Meanie” in the diary, and lamented not only his supposedly cold treatment of her, but of his relationship with a business associate named Francine Tice.

Lanny’s relationship with his son, Radley, was by no means perfect, either. Although family and friends say the two were close during Radley’s adolescence, a bungled firearm business fundamentally tainted their father-son bond. Essentially, Lanny gifted his only son a gun a business as a means of support, but Radley’s lack of business acumen predictably led to the business going belly-up.

Radley resorted to peddling guns in a far-less legitimate way — out of the trunk of his car — until one day, when he sold to an undercover officer without the proper paperwork. Radley did time for the crime, and was thereafter a convicted felon, making it hard for him to find work and eventually forcing him to move back in with his folks. Radley was thereafter locked in an eternal feud with the man he considered responsible for his lot in life, going so far as to criticize his rather at the man's funeral following the shooting; one relative at the ceremony described Radley’s actions as “character assassination."

Investigators were eventually able to determine that the two people present at the scene of Lanny’s September 2011 murder both appeared to have motive and the means — more than two dozen guns, along with thousands of rounds of ammunition, were seized from the residence during the initial investigation — to shoot Lanny nine times.

But, after questioning Radley about his recollection of what happened on Sept. 30, the pages of Donna’s diary, as well as her peculiar actions observed on the night of the murder, proved to be what police needed to pursue murder charges.

Not only did Radley’s story of waking up to the sound of gunshots, followed by “dry fire” — the clicking sound made by the trigger of an unloaded firearm as it’s being pulled — check out, but police learned that Lanny was due to go to North Carolina that morning with Donna’s nemesis, Francine, and had only found out hours before his scheduled departure. Donna’s diary entries about Francine made it clear she thought that her and Lanny were much more than just “business associates,” which meant that Donna was likely enraged at the thought of the two of them gallivanting in North Carolina together.

Additionally, investigators realized that if Radley was able to actually hear a gun dry-firing on the opposite side of what was essentially a mansion, the sound of actual gunfire must have been deafening inside the Horwitz household — a realization that cast suspicion on Donna’s claim of “not being able to hear anything” when authorities arrived following the murder.

Donna Horwitz was arrested a week after Lanny’s murder and charged with murder.

On Jan. 17, 2013, she was found guilty of first-degree murder and was given the mandatory sentence of life in prison, the Palm Beach Post reported at the time., despite the fact that her defense team tried to pin the murder on Radley by using his past felony and passion for guns against him.

“What you have here is a woman scorned,” Assistant State Attorney Aleathea McRoberts told the South Florida Sun Sentinel at the time (McRoberts was also interviewed for the “In Ice Cold Blood” special on the case). “It’s the oldest motive in history. Love, hate and obsession can bring a woman to kill and blame her only son.”

But after spending several years in prison, Donna Horwitz received a retrial after judges with the 4^th District Court of Appeals in West Palm Beach overturned her original conviction on the grounds that her silence prior to her arrest should not have been used as evidence, the Sun Sentinel reported in February 2015. She was ultimately found guilty once again, this time of second-degree murder, and sentenced to 32 years in prison — technically a lighter sentence, although she was already 71 years old at the time of the verdict.

And, despite the fact that Donna’s defense team again tried to point the finger at Radley for the crime, he told a local CBS affiliate at the time that he doesn’t hate his mother for what she did, adding that his father had been abusive at points in their relationship.

"No matter what happens in life, just bite your tongue and hold your temper," he told the Sun Sentinel in October 2017. "Because it doesn't take much to push people over the edge."