Kellene Stockwell & Brandon Rittiman
Channel 2 News

A lab investigator testified Thursday about the crime scene where Brianna Denison's body was found.

Photos of Brianna Denison's body were again shown to the jury.

Reno Police Det. David Jenkins testified attackers change their behavior as they see fit over time with their crimes. In this case, he thinks Biela had a realization about using a gun. "A petite sized woman with the reported size of the offender could so easily and physically be overwhelmed and overpowered and that the firearm would actually serve as an impediment to his committing the sexual assault."

Det. Jenkins went on to say that police were very concerned the attacker would strike again so they beefed up patrols around the university. He said when Denison's body was found in south Reno, investigators suspected the attacker had some sort of connection to that area. After James Biela was arrested he found out that he worked near that field at the same company Alberto Jimenez did - the man who found her body in February 2008.

Jimenez testified he found her underneath a Christmas tree while walking to lunch from work. He said the right side of her face was nearly devoid of any flesh. He walked back to work, asked his manager to go back with him to double-check what he saw. They called 911.

Det. Jenkins testified about approaching James Biela's girlfriend in November 2008 after getting a Secret Witness tip about him. "We explained in layman's terms that we could either exclude Mr. Biela as a potential suspect or identify him as the suspect by comparing his biological son's DNA profile to the offender profile."

Also shown was a video taped just after Biela's arrest. Biela and his girlfriend were allowed to meet in the police interview room. Tape shows Biela pacing silently for a long time and breathing heavily.

His girlfriend repeatedly screams "did you do this?"

He does not give a clear answer. He later says, "I can't tell you" when she asks if he did it. "Sorry I ruined your Thanksgiving and your birthday."

Later, he says "it doesn't matter."

She replies with "it matters to me." (She's still asking if he committed the crime.)

"If I told you I did it, are you going to stay with me?" he asks. "Sorry, for being a fu--up."

Two women who were sexually assaulted in late 2007 told their stories last week.

Biela was arrested in November 2008. He's now 28, and could face the death penalty on murder and rape charges in Denison's death.

He's also charged with sexually assaulting the two other women in 2007. 

(The Associated Press also contributed to this report.)