Troy Graves (30) pleaded guilty to kidnapping and seven other counts in a series of attacks on eight women near the Colorado State University campus last year.
During the hearing on Friday, he said he was sorry.
"I understand it's unlikely this single word will perform any miracle healing or anything," Grave said as he choked back tears. "Please understand these apologies are from my heart and let that be a beginning."
In Philadelphia, Graves is accused of strangling University of Pennsylvania graduate student Shannon Schieber (23) in 1998 and of sexually assaulting five women between 1997 and 1999. He could face the death penalty in that state.
District Judge Terence Gilmore said he imposed a life sentence because of the nature of the crime and the victimisation and fear caused by the defendant.
Graves, who was a senior airman at FE Warren Air Force Base in Cheyenne, Wyoming, is still in the Air Force. Warren base spokesperson Sergeant Kurt Arkenberg said officials will review his case before taking any action. - Sapa-AP