Who were the only two suspects in Lanny Horwitz's murder? Details explored ahead of Mother, May I Murder on ID

Lanny Horwitz, a successful Florida businessman and real estate mogul, was shot to death in September 2011, in the same house where he lived with his ex-wife Donna and their adult son, Radley. The latter was reportedly sleeping at the time and only woke up to the sound of gunfire. Meanwhile, Donna claimed she heard no such noise. She was eventually convicted of the murder.

Detectives investigating Lanny's murder believed Donna murdered him over this close friendship with his business partner Francine Tice. She had written about her feelings of jealousy in a journal and suspected that they were more than just close friends and business associates.

Donna Horwitz was tried in January 2013. Her defense team tried to pin the blame on the former couple's son Radley. Regardless, she was eventually found guilty of murder.

An all-new episode of Mother, May I Murder? on ID revisits Lanny Horwitz's shooting death this Monday, August 7, 2023. The episode, titled Nine Bullet "Suicide," will air on the channel at 10 pm ET.

Here's a look at the official synopsis:

"Police reveal a suspected suicide as a brutal nine-shot execution with only two suspects, the victim's ex-wife and their son; that son, Radley Horwitz, recalls the toxic series of events, which he says triggered his mother's murderous act of rage."

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Out of the two suspects, the son and the ex-wife, the latter was convicted in Lanny Horwitz's shooting death

There were only two other people present in the house when the incident occurred - Horwtiz's ex-wife and high school sweetheart Donna Horwitz and their adult son, Radley. Suspicion fell on both of them. The latter claimed he had been sleeping and was only awakened by the sound of gunfire. Donna, however, asserted that there was no such noise.

While investigating the businessman's murder, police learned that he and Donna shared a rocky relationship. They had been together for decades, but were married and divorced twice over the years. The couple had only reconciled recently, not long before he was gunned down.

Police also found Donna's journal, in which she had written about her jealousy over Lanny and his business partner Francine Tice's close friendship. She suspected they were more than just work friends and expressed her envy in multiple entries. This made authorities suspect that Donna could have a possible motive for the murder.

Donna Horwitz (Image via @ChuckWeber12/Twitter)

Within a week of Lanny Horwitz's shooting, Donna was arrested and charged with first-degree murder. Her trial took place in January 2013, when things took a dramatic turn as the defense tried to pin the blame of the former couple's son, Radley, who was a convicted felon. They suggested he wanted to claim half-a-million from his father's insurance policies.

At the time, Radley Horwitz was a single father and a former licensed gun dealer. However, he had previously been convicted of selling a firearm to a felon, as a result of which he was sent to prison for five months. After his release, he faced several issues finding work, given his past as a convicted felon. His need for money was pinned as his motive behind the murder.

However, Radley's version of the events surrounding the shooting seemingly matched all the evidence found at the crime scene.

Donna Horwitz was ultimately found guilty of the first-degree murder of Lanny Horwitz and sentenced to life in prison. But her conviction was overturned four years later, leading to a re-trial in 2017 when she was once again convicted of a lesser charge of second-degree murder. This time, she was sentenced to 32 years in prison and is now serving her sentence at Florida’s Lowell C.I.

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Lanny Horwitz's murder case features on ID's Mother, May I Murder?