Lets be real here. Anyone who willingly gets evidence of a murder tattooed on themselves is a fucking retard. Had it not been for that tattoo, the case would probably still be unsolved.
I think that the detective is smarter than this guy is dumb though. Solving a cold case by using a tattoo as evidence is epic. You know what his co-workers are going to be talking about next Monday by the coffee machine.
I found this interesting too, you would never expect people to be so stupid. My dad was telling me about this the other day and I saw it on the news too.