The former "Frasier" and "Cheers" star was expected to argue against Freddie Glenn's release at his parole hearing Monday, however, the actor missed his flight and was not able to attend.
Karen Grammer, 18, was abducted outside the Colorado Springs Red Lobster where she worked by three men after a botched attempt to rob the restaurant.
She was blindfolded and dragged along as the trio held up a convenience store, then taken to an apartment where she was sexually assaulted for hours before her throat was slashed and she was stabbed in the hand and back, police said.
Glenn, 52, also is serving a life sentence for his role in the deaths of two men prior to the Grammer slaying.
The Denver Post said Colorado parole-board members decided not to release Glenn after they heard from a former prosecutor, a homicide detective and family members of Glenn's victims.
"This is a butcher. This is a monster," the Post quoted Kelsey Grammer as writing in an e-mail message to the parole board.
"I can never escape the horror of what happened to my sister," Grammer added.
"When we heard this man might be paroled, the suffering began anew."
"I apologize for my participation in something so terrible," Glenn told the victims' families. "I am sincerely and truly remorseful. ... I am very, very sorry."
The next parole hearing for Glenn will be scheduled in five years, the newspaper said.
Copyright 2009 by United Press International.