Omar? Sounds Swedish.
Omar is not unusual among non-Muslim Mexicans, for some reason. They may have been naming their children after Hollywood actors (in this case, possibly the handsome Omar Sharif) or some such thing, and then it just became a regular name as Mexico became less Catholic.
That said, I’d bet this was a workplace thing. He may not have worked for the bank itself, but he probably had some connection with somebody on the premises, perhaps in another business, and was trying to get back at that person.