DAYTON — She was China Arnold's cellmate and lover, but after Arnold admitted killing her baby in a microwave, Linda Williams wanted out.

"I requested to leave the cell we were in," Williams testified Thursday in Arnold's aggravated murder trial. "I didn't want to be there anymore."

Williams, the first witness called by prosecutors, said the two became friends, and eventually had a sexual relationship, when they shared a Montgomery County jail cell in March.

She said she asked Arnold if she killed her 3-week-old baby, and Arnold first said she didn't remember.

But on March 27, Arnold woke her in the middle of the night and admitted that she placed Paris Talley in the microwave, turned it on, and walked away. The next day, Williams contacted Dayton police and was interviewed, she said.

Williams, who is visibly pregnant, wept as she told her story to Assistant Montgomery County prosecutor David Franceschelli. But she became defiant when defense attorney Jon Paul Rion questioned her about past legal problems.

Rion also noted that she didn't tell Dayton police everything she knew during that initial interview. Williams said she had "held a lot of stuff back" because she still had feelings for Arnold.

"I cared for her a lot," Williams said. "I was just trying to get justice for the baby."

The prosecution's second witness, Russell Uptegrove, a forensic pathologist with the Montgomery County Coroner's Office, testified that he was initially perplexed by the burn patterns on the baby, which were unlike anything he had seen before.

Autopsy photos showed the baby's torso, thighs and arms covered with bright red burns. Several spectators began crying when those were shown and Arnold was allowed to leave the courtroom.

Paris' DNA was also found on the roof of the microwave, Uptegrove testified.