Sgt. Jennifer Pound of the Integrated Homicide Investigation Team says James Saar is accused of killing Troy Robert Squires at Mission Institution on Dec. 2, 2011.
Squires was being held as a dangerous offender at the prison when he was killed, while Saar was serving a life sentence for murder and aggravated assault.
Pound says several people were initially arrested after the murder, but through the process of elimination and help from forensic work, Saar was identified as the key suspect.
After Squire's murder, Saar was moved to a maximum security prison outside of B.C.
He would have been eligible for parole in 2017, but will now face the new murder charge.