RUTLAND, Vt. (AP) - A dead cell phone, a missed connection with friends, a chance encounter with a seemingly helpful stranger.

Testimony in the case of a man accused of raping and killing a University of Vermont student got under way Thursday, with Michelle Gardner-Quinn's friends describing the night of revelry that turned into tragedy after she got separated from them and borrowed a cell phone from a man on the street in hopes of reuniting.

The stranger was Brian Rooney, 37, of Richmond, who allegedly killed her in a late-night attack that began with the happenstance meeting on a downtown Burlington street.

Prosecutors say Rooney took her to Huntington Gorge in Richmond, where he sexually assaulted her and then killed her to cover it up. Her body was found six days later, stuffed into a rock outcropping near the gorge. She had been strangled and beaten.

Rooney, who is charged with aggravated murder, has pleaded not guilty. The case was moved from Burlington to Rutland - about 70 miles away - because of pre-trial publicity about the killing, which Rooney's lawyer said would have made a fair trial impossible in Chittenden County.

If convicted, he would get life in prison.

In opening statements Thursday, defense attorney David Sleigh told jurors the linchpin of the state's case is DNA evidence taken from a small sample and analyzed by a state laboratory with a history of errors.

Assistant Attorney General Matthew Levine said Gardner-Quinn, 21, of Arlington, Va., was a victim of bad luck - and Rooney.

"How did a bright young ecology major wind up as prey in the hands of an older stranger?" Levine told the jurors in Vermont District Court. "The answer's simple. Bad luck, a twist of fate and a crime of opportunity.

"The bad luck was her dead cell phone battery. The twist of fate: a hand offering help that turns into the hand of a killer. And the crime of opportunity: a decision by Brian Rooney to take advantage of a young woman alone late at night," he said.

He told the seven-woman, five-man jury that a DNA profile developed from semen found on her body matched Rooney's profile, and that surveillance camera video from a jewelry store captured the two walking up Main Street toward the campus about 2:30 a.m.

Sleigh dismissed the state's case as thin, saying it hinges on "two nanograms" of "alleged seminal fluid" and that the physical evidence that should've resulted from a forced rape and killing - in his car, in his home, on his clothing - was conspicuously absent.

Gardner-Quinn, a recent transfer to the University of Vermont who was majoring in environmental studies, spent the early part of Oct. 6, 2006 celebrating the birthday of friend Dorsey Kilbourn with Kilbourn's parents and students. having dinner out and then drinks at downtown bars.

"After 2:25 in the morning, the state's evidence becomes quite a bit less detailed and quite a bit less clear," he said.

After getting separated from her friends, Gardner-Quinn was thwarted at reaching Kilbourn because her cell phone battery died. That's when she came across Rooney on the street.

She borrowed his and called friend Tommy Lang to ask where she could reunite with Kilbourn, 22.

Moments later, Lang called back and Rooney answered.

"He said something to the effect of "I guess you want to speak with this beautiful brunette standing next to me' and I said "Yeah,"' Lang, 23, of Portland, Ore., testified.

Lang tried to call Kilbourn to find out where she was so Gardner-Quinn could join her, but her cell phone was set to vibrate in her jacket, she testified. The next morning, she realized she had 10 voicemail messages from him, she said.

"The last time I talked to her, she said "I'm walking down the street. Come outside and meet me.' I waited for 10 minutes to meet her and she never showed up," Kilbourn said.

Rooney told police Gardner-Quinn left him to catch a cab back to her dormitory.

The two were captured on surveillance cameras from Perrywinkle's Fine Jewelry store that showed them walking side by side on the sidewalk past the jewelry store, heading away from downtown and toward campus.

The images were located by Burlington police Detective Andrew Frisbie, who had been dispatched to downtown businesses after Gardner-Quinn's disappearance to look for any that might have captured her image.

He described the emotional scene at the jewelry store when Gardner-Quinn's parents, John Charles Quinn and Diane Gardner-Quinn, her brother, Paul, and Lang were shown the images.

"Their reaction was instantaneous, and very emotional.

"John put his head in his hands. Paul walked out in the hallway and started to cry. Diane became very emotional. It was a very spontaneous moment," Frisbie said.

Sitting in the front row, Gardner-Quinn's sister, Yasmine Hassam, sobbed softly as the images were shown on a projector in the darkened courtroom.

AP-ES-05-15-08 1611EDT