DENVER - Troy Graves arrived in Colorado yesterday to begin serving his life sentence.

The transfer from Philadelphia of the serial rapist who terrorized women in two states was in keeping with a plea bargain in which he admitted murdering University of Pennsylvania graduate student Shannon Schieber, 23, and attacking five other women in Philadelphia and seven in Fort Collins, Colo.

In exchange for his guilty plea, prosecutors agreed not to seek the death penalty against Graves, 30, and let him serve his time in Colorado.

Graves arrived in Denver shortly after noon local time and will spend up to a month at a diagnostic center in Denver before officials decide which prison he should be sent to, said Colorado Corrections Department spokeswoman Alison Morgan.

Graves, the man known as the "Center City Rapist," struck in Philadelphia's Rittenhouse Square neighborhood six times between June 1997 and August 1999, typically entering victims' homes through an unlocked window or balcony door.

He was captured after police used DNA evidence to link him to a string of similar attacks on women near the Colorado State University campus.