Police in Barrie, Ont., have laid dozens of charges against a father and son whose home was so packed with explosives it prompted a week-long evacuation last month.

William Feldhoff, 75, and his son Donald Feldhoff, 54, each face 44 charges related to improvised explosive devices and chemicals found as police combed through the house and a hidden bunker.

The elder Feldhoff also faces another 39 charges for firearm offences.

Both were already charged in the 1978 cold-case homicide of Michael Traynor, with Donald Feldhoff being charged with first-degree murder and his father facing an accessory after the fact charge.

The homicide investigation spurred police to examine the residence the men shared, a search that led to the discovery of a two-room bunker dug into the backyard and temporarily forced roughly 60 neighbours from their homes.

Police say they eventually found 26 illegal firearms, 11,000 rounds of ammunition and more than 80 explosive devices.