TALLAHASSEE, Fla. (AP) — A Florida dentist on trial in a murder-for-hire case involving his ex-brother-in-law claimed Thursday that he was a victim of extortion by the killers, but wasn’t actually involved in the plot to kill the prominent Florida State University professor.

Charles Adelson, whose sister Wendi was in a bitter custody battle with professor Dan Markel when Markel was shot in his car outside his Tallahassee home in 2014, testified in his own defense. He said his ex-girlfriend told him an ex-boyfriend committed the crime and now wanted Adelson to pay more than $300,000 or he would be killed, too.

“I’m not going to be part of paying for a murder. This is insane,” Adelson said he told his ex-girlfriend, Katherine Magbanua. “She’s like, ‘Look. If you don’t pay in 48 hours, they will kill you.’ I said, ‘Katy, I feel like I’m being extorted.”

Previously, Dan and Wendi Markel had divorced and were granted shared custody of their two children. But Wendi wanted to move from Tallahassee to South Florida to be closer to her family. A judge ruled that Wendi couldn’t move the children from Tallahassee and Dan Markel refused to move to South Florida.

Prosecutors contend that Adelson paid to have the professor killed and that Magbanua hired Sigfredo Garcia, the father of her two children, to commit the murder and that he enlisted the help of his childhood friend, Luis Rivera. Magbanua and Garcia were convicted of first-degree murder and Rivera is serving a 19-year sentence after pleading guilty to second-degree murder in exchange for testifying against Garcia and Magbanua.

Adelson is charged with first-degree murder, conspiracy and soliciting the killing, but he testified Thursday that investigators got the facts wrong.

“They think it was murder-for-hire. It was an extortion,” Adelson said.

According to his testimony, events played out like this:

Before the killing, Adelson’s family offered Markel $1 million to move to South Florida so the children could be near his ex-wife, he testified. Adelson said he offered to pay one-third of the cost. He told Magbanua, who he was dating at the time, details of the conversation and the contentious custody battle.

Magbuana asked Adelson if he’d have to take out a loan to pay his share, and he said no, he could just write a check. He also said he bought his sister a $5,000 television when she was going through the custody battle and joked it was cheaper than hiring a hitman. He repeated the joke many times before Markel was slain more than a year later, but said it was only a bad joke and he never sought to hire a hitman.

When Magbanua told Adelson her fried had killed Markel, she said it was because she shared details of the custody battle and the $1 million payment offer, according to Adelson.

“She said, ‘Listen, this is all my fault. I had no idea that anything was going to happen. It was totally my fault,’” Adelson recalled.

Adelson said he went to his safe and gave her $138,000 in cash and said that he could pay the killers $3,000 a month after that. He said he didn’t go to the police because he was afraid Garcia would kill him.

He said he didn’t think Magbanua was part of the extortion plot or the murder, but was instead trying to protect him from Garcia. He testified she later told him she wasn’t getting a cent of the extortion money and he agreed to separately give her $1,000 a month to help her pay for health insurance for her children, even though the couple had already broken up.

Prosecutors plan to cross-examine Adelson on Friday.