OK, that was beyond naivety, that was pure retardness. Literally all parties are guilty of it. Horse face by leaving culprit with Legosi, Legosi by everything he has done, and Maron by not killing him.
More than likely, Yafya was using this as a way to show Legosi that his fairy tale world doesn't exist... that inter-species couples are impossible.
Which is pretty damn ironic, since Legosi already knows the hell it is to be a hybrid... he just needs to remember his mom. Legosi just prefers to live toward the ideal than accept reality, which Yafya has done.
You know Legosi, adoption is an option.
Good idea, Yahya. Leave the kid who has a unique similarity with the criminal (being hybrids). I'm sure that criminal won't psychologically trick the kid. Starting to think you're doing everything on purpose.
"Here's a key to this guys shackles, his loaded gun and a button, that will erase history if pressed. I'll go now, so don't do anything stupid, till I'm back."
Highly-likely this was the plan all-along, but still...