COLORADO SPRINGS, Colo. -- A man convicted in a string of murders, including the rape and slaying of actor Kelsey Grammer's sister in 1975, has waived his parole hearing.

Freddie Lee Glenn, 50, is being held at the Bent County Correctional Facility in Las Animas, where he is serving life sentences for three murders in 1975.

One victim was Karen Grammer, 18, who was raped and stabbed by men trying to rob a restaurant where she worked. She was waiting outside for her boyfriend to finish work when Glenn and another man grabbed her because they thought she could identify them.

Grammer was raped repeatedly over a four-hour period then stabbed in the throat.

Glenn was a U.S. Army civilian employee at Fort Carson at the time of the crime.

In 1976, he was sentenced to die in the gas chamber, but his death sentence was later commuted to life due to a change in state law.

Glenn had been scheduled to meet with state parole board members in January but waived his right to a hearing. Colorado Department of Corrections spokeswoman Katherine Sanguinetti said Glenn would be eligible for a hearing again in six months.