Raleigh, N.C. — After the testimony of several mental health professionals Thursday, the defense rested in the murder trial of Joshua Stepp.

Stepp, 28, is charged with the first-degree murder of his 10-month-old stepdaughter in November 2009. He has admitted to beating, shaking and slamming Cheyenne Yarley into the carpet when she wouldn't stop crying, 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.

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

Forensic psychiatrists Dr. Nicole Wolfe and Dr. Jonathan Weiner testified Thursday to Stepp's mental condition.

"It was our forensic opinion, both mine and Dr. Wolfe's that the intent was to try to stop this inconsolable baby from crying," Weiner said. Neither doctor believes Stepp intended to kill Cheyenne.

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.

Superior Court Judge Osmond W. Smith III dismissed a juror Thursday after he spotted the juror nodding off during testimony. The juror said he has been under family strain. An alternate will replace him on the panel, which will decide whether Stepp is responsible for Cheyenne's death.