Raleigh, N.C. — A Raleigh man on trial for the beating death of his 10-month-old stepdaughter nearly two years ago took the witness stand for a second day Wednesday, telling jurors that he has recurring nightmares about the night she died.

"It's always on my mind. It's always right there, and it's not going away," 28-year-old Joshua Stepp testified in his first-degree murder trial. "I'd give my life to have her back. She (was) looking at me to be dad, the one whose supposed to watch over her and make sure she's OK. I let her down."

Stepp has admitted to beating, shaking and slamming Cheyenne Yarley's face into the carpet when she wouldn't stop crying on the night of Nov. 8, 2009, but says he doesn't know why he did it.

He testified Tuesday that he was drunk and high on prescription painkillers at the time and can remember only "the most intense" parts of that night.

Defense attorneys working to keep him from facing a possible death penalty say Stepp, an Iraq war veteran, used painkillers and alcohol as a way to treat post-traumatic stress disorder, which resulted from seeing members of his Army unit killed by a roadside bomb.

"I drank all the time," Stepp said. "When I had a free moment, that's what I wanted to do."

The combination of the alcohol, drugs and PTSD along with Cheyenne's nonstop crying led to the crime, Stepp's attorneys contend.

Prosecutors, in seeking the death penalty, say that Stepp also sexually assaulted the child that night. Injuries to her body were consistent with sexual abuse.

During combative cross-examination Wednesday, Stepp maintained that he never sexually assaulted his stepdaughter and that the injuries happened because he was rough with her as he changed her diaper several times that night.

"I hurt her, and I have to live with that. That's my life sentence right there," he said. "But there's no way I could do anything sexual to any of my kids, to any kids period."

Stepp said that he wishes he would have run from his apartment that night, instead of reacting the way we did.

"I didn't mean to do that," he testified. "I pull out her pictures – I just can't say sorry enough."