I've got a mate ... who had a mate, who once staked out a bank for a week because he thought he'd rob it, or someone attached to it.
After going Mon-Thurs from 8am-4pm, parked in their car nearby, it got to 2pm Friday and someone else did in fact rob the bank (they didn't know this at the time), resulting in police coming from all directions. They took off, and thought no more of it.
Two weeks later, Police come knocking ... "Excuse me sir, your car licence plate number XYZ-123, was seen in the vicinity of such-and-such for several days, and you're wanted for questioning in relation to a robbery that took place on the Friday !"
Double FAIL !!!