Something odd going on here. They just didn’t decide to check this guy out because it was Thursday. A similar case to the firemen setting fires in California to get overtime? A firebug or amateur bomber? Something odd.
Vague story about him asking a friend to look after some possessions the day of the explosion. Friend did not look into the box until recently. Reported it to the FBI - presumably in the last few days, which is when this broke.
motive not assertained yet.
Lovers spat perhaps?