A Brooklyn ex-con busted by cops five years ago for keeping an arsenal of guns at his home was found dead yesterday after allegedly setting his attic apartment on fire and shooting himself in the head, authorities said.

Christopher Ocera, 47, was found dead at his apartment in Gravesend after the blaze broke out at 3:15 p.m.

Firefighters had the fire under control by 4:11.

In April 2007, cops found a mortar shell, AK-47 rifle, three pistols and boxes of ammunition while searching Ocera’s home.

He and another Brooklyn man were arrested in the middle of a marijuana deal.

Ocera was charged with weapons possession, resisting arrest and dealing marijuana.

He had lived in the apartment for the past 20 years with his mother.

rich.calder@nypost.com