Investigators believe Stevie Marie Vigil, 22, of Commerce City, legally bought the firearm from a licensed dealer in the Denver suburb of Englewood and transferred it to Evan Ebel, who was a felon who couldn't legally possess a firearm, the CBI said.
Ebel is suspected in the shooting deaths of Colorado Department of Corrections head Tom Clements on March 19 and of Nathan Leon, who was shot March 17 while working as a pizza delivery driver in the Denver area.
Ebel died after a shootout in Texas last week. El Paso County, Colo., sheriff's investigators have said the gun Ebel used in the shootout was the same weapon used to kill Clements when he answered the front door of his home.
The identity of the Englewood firearms dealer wasn't disclosed. Authorities described the dealer as "extremely cooperative" and said the dealer had no knowledge of Vigil's alleged actions after buying the gun.
Vigil was being held on one felony count of unlawful purchase of a firearm. Her bail was set at $25,000.
It's not clear how Vigil and Ebel might have met. Records associated with her arrest have been sealed, and an El Paso County sheriff's office spokesman didn't immediately respond to an email seeking comment.
Ebel, 28, had most recently been sentenced to four years in prison for punching a prison guard in 2008, according to state records. He was paroled Jan. 28 after serving his full prison term, corrections officials have said. His record also includes pleading guilty to holding a pistol to an acquaintance's head and stealing his wallet.
Copyright 2013 The Associated Press.