Atama was reading the news again. He had received a piece of information that the serial killer on the loose has been identified. He did not know shit about who identified him or how his men even got the work done.
Maybe because he did not want to catch this serial killer. Of course, as the minister, he was losing men and citizens; but as Hiro's teacher, he knew if that serial killer is caught, their lie will be revealed.
Onogi broke in through the border? The end of the story. Onogi will attack the Ministry or the mages will fight the scientists as a form of revenge, and if he tries to stop anyone, they will disregard him.
He was at the risk of losing his position as the headmaster, then he would be unable to cover for Hitori's crimes. He had to save his position somehow, but if this murder goes on, he will lose it anyway.