COLUMBIA, Mo. -- Jurors didn't believe the testimony of a former Columbia police officer convicted of killing a gay college student with whom he had an affair, a jury member says.

Jared Buchan was on the jury that convicted Steven Rios, 28, Saturday of first-degree murder and armed criminal action in the death of Jesse Valencia, 23. The Clay County jurors were brought to Boone County to hear the case presented by Cape Girardeau County Prosecuting Attorney Morley Swingle.

"I think the most damning thing was when he took the stand himself," Buchan said.

Swingle said that he had noticed jurors weren't moved when Rios cried while he was on the stand.

"Their arms were crossed, and they had stoic faces," he said. "I knew not one was convinced by him."

Valencia, who attended the University of Missouri-Columbia, was last seen at a party early June 5, in his neighborhood east of campus. The student's body was found later that day in a nearby yard.

Public defender Valerie Leftwich has said she plans to appeal the verdict.

Rios had arrested Valencia in April 2004 for interfering with him and another officer as they answered a police call about a loud party.

In testimony Friday morning, Rios said his affair with Valencia began later that night. He told the jury that he visited Valencia's apartment six times, including three times while he was on duty.

Rios also acknowledged lying about his affair with Valencia but said he did not kill the college student. He testified that he was with co-workers when Valencia was killed.

Key evidence included DNA recovered from under Valencia's fingernails and hair found on his chest, both of which matched Rios.

Buchan said it was damning evidence but that the jury "had to go beyond the DNA."

Buchan, of Kansas City, said most of the nine hours the jury deliberated were spent discussing the murder weapon, which was never found, and whether Rios had enough time to slash Valencia's throat between leaving the police department at 4:47 a.m. and arriving home at 5:20 a.m. or 5:25 a.m.

"I tried to relay to the other jurors that this is not Kansas City and that it wouldn't take much time to get from one place to the other," said Buchan, who said he has visited Columbia often.

Jurors also decided that a police officer would know how to hide evidence, Buchan said.