Pepe insinuated prozzies, I insinuated cocaine, most people seem to agree with Pepe, but I'm sure neither of us will take any satisfaction in being right if the truth ever does come out.
I would say it is more likely the guy following him was hassling him about whether he wanted a hooker or drugs, those scumbags can be quite persistent, he probably eventually told this dude to fuck off and then your man probably lost the head and killed him.
People are always telling scobes to fuck off though, you'd think they'd be inured to it by now.
Also, it doesn't seem like your regular street fight/mugging where the victim is left bleeding on the pavement, they would seem to have put some effort into concealing the body.
Did he withdraw money from the ATM at that time? I thought he was captured on CCTV passing it, not using it.