Roland Reaves, 47, is up for a March 30 parole hearing.
He was convicted of killing Officer David Cole during the July 1974 robbery of a convenience store that used to be on Florence Avenue in Walnut Hills.
At the time, Reaves was on the run after killing his wife in Chicago by leaving her in the trunk of a car, where she froze to death, according to the Greater Cincinnati Police Museum.
After repeatedly shooting the officer, who was only 23, prosecutors say Reaves ordered his accomplice, Ricardo Woods, to fire the kill shots.
Reaves and Woods were both sentenced to death. But those were commuted to life when Ohio's death penalty law was declared unconstitutional in the 1970s.
Then, Woods was paroled in 1994 without prior notice, according to the museum and prosecutor's office.
The officer's widow, Cheryl Cole Candelaresi, said she found out by reading it in a newspaper.
This time, she is vowing Reaves won't walk free.
Hamilton County Prosecutor Joe Deters, Assistant Police Chief Dave Bailey and Sgt. Dan Hils, police union president, are urging the public to send emails opposing his release to Ohio Parole Board. Click here to send one.
"That this defendant is even being considered for any type of release is appalling considering he was originally sentenced to death," reads a prepared statement about the case on the prosecutor's office website.