Brian Winchester, who confessed last year to killing his best friend Mike Williams so he could spend the rest of his life with his wife, Denise Williams, told jurors Tuesday in detail how they planned to kill him and cash in on his insurance.

Winchester, emotional and choking back tears on the witness stand, took jurors through his twisted relationship with Denise Williams, from the day they began having an affair in 1997 to the morning he killed her husband on Lake Seminole in 2000 and beyond.

DAY 2 updates:Brian Winchester says Denise Williams 'was in my head with me' when murdering her husband

Under questioning from Assistant State Attorney Jon Fuchs, Winchester also walked jurors through the aftermath of the killing, his doomed, short-lived marriage to Denise Williams and their descent into paranoia as family members, law enforcement and the media began to suspect that Mike Williams didn’t die in a simple boating accident.

“We promised each other neither one of us would ever say anything,” Winchester said. “Because we knew the only way they’d get anything is if one of us talked.”

Mike Williams murder:Complete coverage of Day 1 of Denise Williams trial

Winchester, 48 and serving a 20-year sentence for kidnapping Denise Williams in 2016 after their relationship unraveled, testified as part of an immunity deal with prosecutors. As part of the deal, his testimony can’t be used against him in Mike Williams’ killing.

Before Winchester took the stand, Fuchs and defense attorney Philip Padovano delivered their opening statements in the trial of Denise Williams, who was arrested May 8 on charges of first-degree murder, conspiracy to commit first-degree murder and accessory after the fact.

Fuchs said jurors will never hear a flat-out admission from Denise Williams that she masterminded his killing with her lover Winchester so they could be together and she could collect $1.75 million in life insurance.

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But he said jurors will hear a recording of Denise Williams in 2016 telling Winchester’s ex-wife Kathy to tell his father after his arrest on kidnapping charges that she “didn’t say anything to the Florida Department of Law Enforcement,” which was investigating the couple for the murder.

“Why would that be a message you have to send?” Fuchs asked jurors. “In the end, the state is going to ask you to end the 21 years ... of sex, lies and deceit and find her guilty of these particular crimes.”

Winchester has 'motive to lie'

Padovano told jurors there is no doubt Brian Winchester killed Mike Williams. But he said there was no evidence — beyond the testimony of a confessed killer — that Denise Williams had anything to do with the murder. He said there is no DNA or fingerprint evidence, no witness who overheard Winchester and Denise Williams plot to commit the murder.

“There is no tangible evidence or physical evidence tying Denise Williams to this crime,” said Padovano, a retired judge. “The issue you’re going to have to decide is whether to believe him. All you’re going to have to go on is the word of the man who actually committed the murder.”

Fuchs didn’t mention the immunity deal with Winchester. But Padovano told jurors about it in his opening statements.

“He will be able to testify as he pleases about this without any fear that the state will be able to use that testimony against him,” Padovano said. “Mr. Winchester has a motive to lie to you. He has a motive to make up this accusation against Mrs. Williams. He didn’t mention anything about her alleged participation in this murder until he realized he was facing a life sentence in this kidnapping and after he realized Mrs. Williams was going to go into court and ask for a life sentence.”

Throughout the testimony, the jury was attentive and asked no questions. Denise Williams sat impassively during her ex-lover's testimony, not betraying any emotion. Winchester is expected to face cross-examination from her lawyers on Wednesday.

Several other witnesses also took the stand Tuesday, including FDLE special agents who worked the case and others who took part in the massive, weeks-long search for Williams on Lake Seminole. But Winchester’s testimony was by far the most dramatic of the day.

Illicit love affair began at concert

Handcuffed and clad in a blue prison uniform, he described in detail how he and his wife and the Williamses had been close friends since their days at North Florida Christian High School and later at Florida State University. After college, they grew even closer, partying together, going to see concerts and, after one night in particular, talking about sex. Something sparked between him and Denise Williams, he testified.

On Oct. 13, 1997 — a day Winchester and Denise Williams would later consider their anniversary of sorts — the two couples went to see a Sister Hazel concert at Floyd’s Music Store on the West Tennessee Street strip. As Mike Williams and Kathy Winchester parked the car, he and Denise Williams kissed and made out inside the club.

They went dutifully to their respective homes that night. But Winchester and Denise Williams spent the night talking and having phone sex, he said.

“We just connected like nobody else,” he said. “It snowballed really fast.”

They started meeting whenever they could when Mike was working or attending out-of-town conferences. Brian would park his car at a church on Meridian Road and walk along a drainage ditch through the woods to her house on Starmount Drive for rendezvous. They took trips together to Destin, South Beach and New York City. Winchester even secretly tagged along when Denise Williams went out of town with her husband for a conference.

During his open statement, Fuchs said before Williams was killed, Winchester, his then-wife Kathy and Denise Williams had sex together in Panama City.

About a year into their affair, Winchester and Denise Williams started talking about wanting to be together and how to make that happen. Denise Williams, who came from a religious family, didn’t want to get a divorce or share custody of their young daughter with Mike Williams.

“The more we were together, the more we wanted to be together,” Winchester said. “Overall, it was very mutual. We wanted to be together — and we weren’t going to let anything stop that.”

'It would be up to God'

It wasn’t long before their talk started to include murder, Winchester said. They discussed killing Mike Williams in a staged robbery at his office late one night but ultimately rejected that. They discussed taking a boat out in the Gulf of Mexico and tossing their spouses overboard in a staged accident that only they would survive. But Winchester said he couldn’t kill the mother of his child.

Winchester and Brian Williams went on a hunting trip to Arkansas, and at one point, Williams fell in quicksand-like mud. Winchester rescued him but realized he could have left him there to die. He later shared the story with Denise Williams. It seemed to inspire their idea of getting rid of Mike Williams in a boating accident, he said.

“Denise liked this idea. She felt better, I guess, about herself — or we could feel better about ourselves — if there’s a chance that he could make it out of it," he said. "I think there was even talk that it would be up to God what happens. Not us. It won’t be a murder. It will be an accident. It’s kind of screwed up thinking. But that was a scenario that she could live with, I guess.”

Winchester went on to detail how he lured Mike Williams out to Lake Seminole, encouraging him to put on his waders, motoring out on the water into the darkness and pushing him out of the boat. When he surfaced and began struggling, holding onto a tree stump, panicked and confused, Winchester didn’t know what to do.

“I didn’t know how to get out of that situation, so I loaded my gun and made one or two circles around and I got closer to him and he was in the water and as I passed by I shot him,” he paused, “in the head.”

'I was just lying'

Wiping his nose and eyes with a tissue, he continued, explaining how adrenaline enabled him to pull Mike William's dead body from the water and into the back of his Suburban. As he drove back to Tallahassee, he tried to figure out where he was going to dispose of the body.

“It had to be close and it had to be quick and obviously it needed to be a location where he wouldn’t be found,” he said. “I saw blood coming out of my tailgate, and that freaked me out.”

Winchester settled on Carr Lake in northern Leon County. He stopped by a Wal-Mart to buy a shovel, a tarp and weights to keep the body submerged and said he ran into a friend, Mike Phillips, who asked if he was headed to join the search. He pressed on to the lake, which was dry at the time, and dug a hole at the edge of the lake bed. As he did, Winchester said he was bitten by ants and worried their red sting marks would give him away.

He tried rinsing the blood out of his vehicle with a hose at his parents' house. When that didn’t work, he went to a car wash at Tharpe Street and Old Bainbridge Road, using a pressure washer to get rid of the blood. He drove to Cairo, Georgia, to attend a Christmas party with in-laws that afternoon.

On the way back, he got a call from his father, Marcus Winchester, telling him Mike was missing. He and his father drove out to Lake Seminole that night and joined family and friends in the search.

“He was searching and I was just lying,” Winchester said, crying at the mention of his father. “My dad didn’t want to give up. My dad loved Mike.”

Winchester doubled over unable to continue speaking. The judge called for a 10-minute break.

Collecting the insurance money

When he and the jury returned, Winchester went on to describe how he and Denise Williams worked to keep the murder secret. They didn’t talk for the first few days after his death. It was even longer before they met in person.

“I remember being kind of nervous,” he said. “And I just knew it would be kind of weird to see her because of what we had done. But as the search went on and long-term as things got back to normal, we just kind of settled back into the same routines.”

But they had to deal with the fact that his body hadn’t been found.

“And so the concern between she and I then became well if his body’s not found, what’s going to happen with the life insurance?" Brian said. "Is she going to get the money or not?”

More:Denise Williams charged with insurance fraud in Mike Williams death

Winchester wasn’t in a hurry to collect on Mike Williams' three life insurance policies — one of which he wrote months before killing him. At the time, the life insurance money was earning 8 percent interest, something they couldn’t get at a bank.

“I felt like we needed to kind of lay low on that and not appear to be the eager widow ready to cash in her life insurance," he told jurors. “I knew the longer it dragged out, the better it was going to be. We talked about that.”

Eventually, they learned she would need a death certificate to collect the money, which she got through a judge in July 2001. In 2005 the two finally married.

Paranoia sets in

Over time the couple grew paranoid. The concern was heightened when Denise Williams brought her and her late husband’s daughter over to his mother Cheryl Williams’ house a few years after his disappearance. During the visit, she found and read a notebook Cheryl Williams kept detailing her suspicions about them.

Denise Williams, he said, "really freaked out about it." Soon enough, her mother-in-law would not be allowed to see her granddaughter again.

The couple began to feel the heat from law enforcement. Winchester agreed to an interview at FDLE headquarters on Phillips Road.

“It became quite clear to me from that interview that they were suspicious of what happened and not only that, they were suspicious of me and Denise,” he said.

They became convinced they were being monitored and took to leaving their phones in the car and meeting in parks to discuss the investigation. They even used hand signs to signal when they needed to talk — a "C" for Cheryl and two clenched fists for prison bars.

'Can't trust Denise'

But they had their pact — their "agreement," as they called it. Neither would ever squeal on the other.

“We were pretty arrogantly confident in that agreement, I guess," he said.

But he began to have his doubts. He recounted a warning from Kathy Winchester.

“You can’t trust Denise," he said she told him. "And she will throw you under the bus the first chance she got.”

News Director Jennifer Portman contributed to this report.