Update: Peter Williston was convicted late Wednesday afternoon, Feb. 5, 2020

A former Birmingham police lieutenant charged with raping his stepdaughter said he only slept with her to solve a problem she presented to him.

Peter Williston, 50, is charged with first-degree rape. He took the stand in his own defense Wednesday. “I recognize it was disgusting and inappropriate,” Williston said during his testimony. “I was an adult. I should have known better.”

Jefferson County Deputy District Attorneys Jessica Hebson and Jason Wilson argued Williston, who resigned from the Birmingham Police Department after his arrest in 2018, used his authority as the victim’s stepfather-- and as a law enforcement officer-- to force the then-teen to have sex with him.

The stepdaughter testified Tuesday that the sexual encounters began when she was 14 and in the ninth grade. The former cop said he first met the victim when she was three and he was dating her mother; Williston and the victim’s mother married when she was six years old.

Williston admitted to having sex with his stepdaughter, but said he didn’t start the relationship until she was 16--the age of consent in Alabama. Williston also said the sexual relationship was a mutual agreement between he and the teen.

Williston said his stepdaughter, now a 26-year-old mother of three, approached him when she was 16, in the spring of 2010, about a problem she was having at school. Williston said he offered to assist her with that problem, and the two entered into a “mutual agreement” that Williston would “assist” his stepdaughter with any sexual needs she had, he said. If the victim had sex with Williston, he said, she wouldn’t have to worry about her problem at school. He was 40 years old at the time.

“I knew that it was not the best thing to do,” Williston said.

The step daughter had testified Tuesday that the sexual abuse began several days after she and her then-boyfriend were alone in the basement and “things got serious.” After forcing her to break up with the boy, she said, Williston came to her. “He said he wanted to have sex with me so I wouldn’t have sex with other people and get pregnant,’’ she testified.

The stepdaughter took several days to think about the arrangement, Williston testified, but later told him that if the sexual encounters would solve her issue, she would be interested. They first had sex several days later.

Williston said he and his stepdaughter only had “normal, standard” sex, and did not use any sex toys or devices, or have oral sex. The relationship lasted until the fall of 2010, Williston said, and they had sex once a week or once every two weeks until that point.

He first told prosecutors he was never physically or sexually attracted to his stepdaughter, but then said after she turned 16, there “may have been occasions” when he was attracted to her during sex.

The relationship stopped because the stepdaughter told Williston her problem was solved and she didn’t want to continue, he said.

Williston said he never forced her to have sex with him, and he never used his position as a police officer to force her to have sex. The victim wasn’t afraid of him, Williston said, but was only afraid of her mother finding out.

In 2012, Williston said the stepdaughter told her mother about the sexual relationship. He admitted that, in one conversation about the relationship with his wife, he stormed off. “I didn’t storm off because of the anger (at the stepdaughter or wife)… I stormed off because of anger towards myself,” Williston said on the stand.

The stepdaughter still lived in the family home with Williston, her mother, and Williston’s two children after revealing the sexual relationship to her mother. After she graduated from high school that May, Williston said she continued to live at home and gave birth to her first child. She eventually moved out in 2013, relocating to Georgia with her husband and child.

The victim, her husband, and children returned to the Williston household years later, after her husband left the military because of an injury. She reported the incidents to Morris police in May 2018 because she said she feared for the safety of other juveniles in the home.

Several of Williston’s claims during his testimony directly conflicted with the victim’s testimony from Tuesday; she said the sex started when she was 14 and lasted until 2011 and that it happened “several hundred” times. The victim has never claimed Williston physically hurt her.

Williston was a 17-year-old veteran of the Birmingham Police Department when he was arrested in June 2018. He was taken into custody after being discharged from UAB Hospital, where he was admitted for several days and underwent psychiatric evaluation amid suicide concerns after charges against him became public.

Before being placed on leave, Williston was serving as the interim commander of the city’s East Precinct. Prior to that, Williston served as the department’s public information officer.

Jefferson County Circuit Judge Stephen Wallace is presiding over the case. Before testimony Wednesday, he upheld the state’s “rape shield” law that prevents any evidence or testimony concerning the victim’s prior sexual behavior or relationships.

Attorney Scott Morro is representing Williston. The defense rested its case after his testimony Wednesday, and the case is expected to be given to the jury by Wednesday afternoon.