A neo-Nazi leader in Florida was sentenced to five years in prison on Tuesday over his stash of explosives, which the authorities discovered while investigating one of his roommates in the killing of the other two.

Officials were alerted in May to the explosives belonging to the neo-Nazi, Brandon Russell, by his roommate Devon Arthurs, who warned them that Mr. Russell had written online about plans to kill people and detonate bombs.

Mr. Arthurs confessed in May to shooting their other two roommates for disrespecting his newfound Muslim faith, the police said.