How detectives uncovered Florida woman's murder inside fixer-upper

In 2018, David Tronnes was obsessed with extensive renovations at the Orlando, Florida, home he shared with his wife, Shanti Cooper-Tronnes, and Shanti's son, Jackson.

The makeover had forced David to live in the garage while Shanti, 39, lived in an apartment above the garage, so when "Zombie House Flipping" came calling, Tronnes, 49, was ready to have his home featured on the reality TV show.

But before the TV show moment came to be, Shanti was found dead in a bathtub.

"She's in her own home, and she's with a man, who is supposed to protect her, who's supposed to care for her, who's supposed to love her. And she certainly didn't deserve the brutality that she suffered," Detective Barbara Sharp of the Orlando Police Department, one of the detectives who investigated the case, told "20/20."

"20/20" explores Shanti Cooper-Tronnes' murder in an episode airing Feb. 23 at 9 p.m. ET and streaming on Hulu the next day with exclusive interviews with the dogged Orlando detectives who kept their eye on David and unraveled the truth.

On April 24, 2018, David Tronnes called the police claiming that his wife, who ran a finance consulting business, was unconscious in their bathroom tub. She was later declared dead.

Jackson, who was 8 at the time, was at school.

David was initially cooperative with investigators, claiming that he last saw his wife in the morning in their home before he went out for a jog with his dogs.

At the crime scene, Shanti's $15,000 diamond engagement ring was missing from her hand, which gave the appearance of a robbery. But no other valuables were stolen.

"Why wasn't the diamond earring stolen if it was a robbery? Why wasn't the cash that was in plain view stolen?" Orlando PD Detective Teresa Sprague told "20/20." "Everything's in plain view."

A few hours into questioning David, the detectives started to get more aggressive as the information relayed by David didn't match up with what investigators were finding at the crime scene.

David claimed that his wife slipped and fell into the bathtub that was filled with water. Shanti, however, was almost dry, and it looked as though the tub hadn't been used in hours, according to investigators. Medical examiners would determine that she was killed by blunt force trauma to the head and strangulation.

"The evidence and her body speak for itself and your story is BS," Sharp told David during the interrogation.

David repeatedly denied having anything to do with his wife's death and that the couple had any marital issues. After being held at the station for 14 hours, the police released David and did not charge him.

But they kept digging into David's life and found there was more to him and his relationship with Shanti.

Although David took the lead in the house renovations, going through contractors and overseeing plans, it was Shanti who paid for the work, according to friends and family.

"I remember hanging out with her and her saying, 'I'm paying for everything. If all of a sudden something happens, he owns this house and I have nothing to it,'" Dana Duran, one of Shanti's friends, told "20/20."

David was put under surveillance and detectives would learn that he was transferring money out of the couple's joint bank accounts and was the sole beneficiary of Shanti's life insurance, which was over $350,000.

"He stood to gain close to $1 million if he was not charged with her murder," Sprague said.

On Aug. 29, 2018, a Florida grand jury indicted David on first-degree murder and he was arrested at his mother's house.

While waiting for the trial to commence, detectives found a key piece of evidence at David's mother's house: Shanti's missing engagement ring.

"He had clearly taken it off of her cold dead body," Sharp said.

David's attorneys argued the ring was never actually missing, that investigators overlooked it when they searched the house.

Investigators would also find writings by Shanti where she expressed her frustration in the marriage.

During the five-day trial in October 2023, prosecutors called "Zombie House Flipping" host Keith Ori to the stand and he testified that he saw a change in Shanti's demeanor when they were in discussions to appear on the show a week before her death.

"She was tense or even intense, [and] appeared to be mildly upset, annoyed, frustrated at something," he testified.

Prosecutors provided forensic evidence that they say showed Shanti was killed in the bedroom, including her blood that was found on the side of their bed.

"He chose to finish her off by strangling her," Sprague told "20/20."

"Watching her suffer for however long," Sharp added.

"Many, many, many minutes, probably," Sprague said.

The defense did not call any witnesses, but argued that investigators excluded other possible explanations for what could have happened to Shanti.

On Oct. 18, 2023, a jury found David Tronnes guilty of first-degree murder. Jackson, who attended every day of the trial, made an impact statement and said that his mother's passing was "like a hole in my heart that I can't fill or fix."

"I was just speaking from my heart," he told "20/20." "And I just wanted people to know how good of a person my mom was, and how she deserved the world, and she did not deserve what happened to her."