Why would they "fear the worst"? Unless this was after an entire day without contact. Why not think maybe she was stuck in traffic, or her car broke down, or she just plain overslept? Over four years' time, even the most trustworthy employee is bound to be late for some odd reason other than becoming a murder victim.
Perhaps the victim had confided in a coworker that she was in fear of the POS psycho.
Good point.