I think the forensic work looks on the wrong aspects. If this guy was really this monster created and protected by intelligence until he wasn't anymore, these traces might be intentionally?

More compelling are possible aliases. That's why no dirt could be found so far except for the obvious things.

Why are there only handshake contracts in the underworld? Try calling the police. That's why your life was always your final payment.

For some things to happen there needs to be only the spoken word.

Drug dealers for example have their lower ranking foot soldiers actually talking over phone if necessary. Voice recognition. You hear for example two people talking and there are many breaks in between. Classy.

Buying drugs? "I am just some dude who was told to wait here and lead you to this place." Same for the money. It is tough, but if one of these foot soldiers get caught they can be easily replaced and really don't know details. That's why the drug business became so violent. More people involved, more people to punish in the worst case, more people tempted.

Fascinating business, but only from the outside.

Same here. Either E wasn't the overlord he is imagined as, or he was. Covert operations are by its very nature covert and not overt.