A man convicted in a decades-old homicide was released from prison Thursday — more than three years after his arrest led to the discovery that his Barrie home was packed with explosives, leading to an evacuation of the surrounding neighbourhood that lasted more than a week.

William Feldhoff, 78, was arrested in 2012 along with his son Donald Feldhoff, 59 for his role in the 1978 murder of Michael Traynor.

Feldhoff was released from the Central North Correctional Centre in Penetanguishene Thursday. He had been sentenced to four-and-a-half years behind bars.

​Traynor's family reported the 26-year-old Barrie resident missing on Sept. 18, 1978. His body was found with obvious signs of trauma in a bush area in Springwater Township, north of Barrie, a few weeks later.

Decades later, in July 2012, William Feldhoff turned himself in to police.  Donald Feldhoff was charged with first-degree murder and his father was charged with being an accessory after the fact.

A subsequent search of the pair's home turned up a trove of homemade explosive devices, two backyard bunkers and unidentified chemicals, prompting the evacuation of 22 nearby homes for more than a week.

A total of 26 illegal firearms, 11,000 rounds of ammunition and more than 80 explosives were found, resulting in an additional 44 charges for both father and son and an additional 39 charges for firearm offences against William Feldhoff.