A man who murdered the sister of Frasier star Kelsey Grammer was denied parole after the actor pleaded against it, calling him a butcher and a monster.

Grammer, whose sister Karen was killed in 1975 aged 18, had been planning to attend Freddie Glenn's parole hearing in Colorado, but missed it because of delayed flights.

Instead he lodged a statement saying: "This is a butcher. This is a monster. I can never accept the notion that he can pay for the nightmare with anything less than his life."

Glenn ,52, is serving a life sentence for the first-degree murder of Karen who was abducted outside a Colorado Springs restaurant, raped and stabbed.

Glenn was also convicted of the murders of 28-year-old motel cook Daniel Van Lone during a botched robbery, and 19-year-old soldier Winfred Proffitt during a drug deal.

Glenn had been given the death penalty but that sentence was commuted in 1978 to life in prison with the possibility of parole. Colorado law no longer allows parole in life sentences for first-degree murder, but Glenn was convicted before that law was changed.

During the hearing, Glenn downplayed his role in the murders and told the board, "I apologise for my participation in something so terrible. I am sincerely and truly remorseful."

In his statement, Grammer said his sister had graduated from high school a year early and decided to take a year off after attending a semester of college. Grammer said she may have moved to Colorado Springs because of a boy she liked.

"She was so smart and good and decent. She wrote poetry ... We could laugh for hours together," he wrote. "I was supposed to protect her - I could not. It very nearly destroyed me... When we heard this man might be paroled, the suffering began anew."

Glenn will be eligible for parole again in 2014.