
.. cause he remembers how MC had a black hole for a stomach..
..He just never realises that MC was so depressed by his absense that he didn't even care about how uncomfortable his hairstyle is for him.
They just missed so much of each other, that they lost parts of themselves as limbs. ML with perfecting his mask. MC by stopping his stories, and only living to see MC on the TV.

.. He has no proof that our ML killed all those people.
Even if he had, all these could be falsified by a higher power than ML, which is the reason why no real suspects appeared. They are trying to bury it because the killer must be related to a higher power than law.
But you have in front of you a kid that lost it all, even his own memories and identity, and the only person who gave him back safety, a place to belong, a family... you decide to accuse him of being his torturer? What the frick is your end-game here?
This detective is the true example of how good-willed people can be the truly A-holes in a story. He may be trying to do the right thing, but by doing it he's destroying our MC's life.
I'm saying it once and twice, ML didn't do it. The real killer is still trying to end MC, so he's protecting him, while knowing he can't get to the real killer because of his power.

... it was a trap, it's obviously a trap.
Sargeant betrayed MC because they ramsoned his (or grand)baby (maybe they kidnapped his pregnant wife or daughter and promised their release if he got MC into the trap)
ML wants MC, maybe he desires him, but most probably wants to destroy him, make him grovel at his feet and show him that there's no hope in this crooked world.
Yaaay!!