SAGINAW, Mich. (WWJ/AP) – A 51-year-old man already serving life without parole in a Michigan prison for a 1991 slaying has received another life sentence for killing his cellmate.

Steven D. Sandison pleaded guilty Feb. 23 to second-degree murder in the Oct. 29 death of 67-year-old Theodore Dyer at Saginaw Correctional Facility near Saginaw. He was sentenced earlier this week to life with the possibility of parole.

READ MORE: Michigan EMS Agencies Seek $20M In State Funding To Address Staff Shortage

Sandison says he killed Dyer — who was serving 25-50 years for first-degree criminal sexual conduct against a child under the age of 13 — because the Grand Haven man was a child molester and wouldn’t stop talking about the case.

Sandison told investigators that he knocked Dyer unconscious and then used Dyer’s own shoelaces to strangle him, The Saginaw News reported.

At sentencing, Sandison said he had no regrets about the crime.

READ MORE: Warren City Council Approves Redevelopment Of Old GM Plant

“I don’t feel bad for what I did,” he said. “I feel bad for maybe his family or something, but as far as remorse toward him, no.”

Sandison, who is now being held in a high-security area at the Ionia Correctional Facility, was initially imprisoned on a first-degree murder charge for killing his girlfriend in Wayne County.

TM and © Copyright 2015 CBS Radio Inc. and its relevant subsidiaries. CBS RADIO and EYE Logo TM and Copyright 2015 CBS Broadcasting Inc. Used under license. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press contributed to this report.

MORE NEWS: DWSD Working To Repair Dozens Of Water Main Breaks