Vermont ? A man seen on surveillance video walking with a college student who was found beaten and strangled a week later was charged Wednesday with murder.

Semen found on Michelle Gardner-Quinn’s body matched a DNA profile developed from a blood stain on Brian L. Rooney’s pants, according to an affidavit filed in court in Burlington.

Rooney, 36, a construction worker and father of three, was a primary suspect in the 21-year-old Arlington, Va., woman’s death. He was the last person seen with her before she disappeared about 2 a.m. Oct. 7 after leaving a bar in Burlington to walk back to the University of Vermont campus. A store surveillance video showed the two walking together.

Gardner-Quinn died of strangulation and “blunt force trauma,” police said in the affidavit. The official charge against Rooney, aggravated homicide, indicates murder during sexual assault or attempted sexual assault. If convicted, he would face a mandatory life sentence.