He had no idea: Police discovered inactive nuclear missile in US citizen's garage. The nuclear missile is harmless because there were no explosives attached.
The missile is a Douglas AIR-2 Genie, an unguided air missile designed for a nuclear warhead. Since it was an inactive item that had not been reclaimed by the military, the man was even allowed to keep the rocket. The Genie missile found is among the first nuclear-equipped air weapons used by the US military during the Cold War. Their production was suspended in 1962.