Michael Moon, 63, is a career criminal who was convicted in 1981 of stabbing to death a woman in Reno, Nevada.
Ten years later, after being released from prison, Moon repeatedly stabbed a man at a bar in Woodstock, Illinois.
He was convicted of attempted murder, and eventually released from prison in 2005.
In 2007, the Escondido Police cold case unit connected Moon to the 1977 murder of a 24 year old man who's body was found inside a home under construction.
"He had significant blunt force trauma to his head, he was strangled and he was stripped naked from the waist down,"said Escondido Police Detective Chuck Gaylor.
After 30 years without an answer, cold case detectives finally solved the case after running a bloody fingerprint in the national criminal database.
The print belonged to Moon.
In December 2008, Moon was convicted of second degree murder but given only five years to life in prison.
"Unfortunately he was sentenced under the sentencing guidelines for 1977, which were much more friendly towards criminals,"Gaylor said.
Last January, Moon was granted parole and has been living in a halfway house in Downtown San Diego.
Detective Gaylor says Moon traveled all across the country working in construction, during the years he wasn't incarcerated.
Gaylor believes Moon may have committed other murders along the way.
"We believe based on his conduct in this murder and the murder in Reno, that it's very likely that he could be a serial killer,"Gaylor said.
This report originally aired on NBC 7 on March 7, 2012.