Why didn't Grayson turn maniac over to the police when he found him?

Grayson didn't turn the maniac over to the police because he believed that the authorities would not be able to handle the situation effectively, possibly due to corruption or incompetence. Additionally, he might have felt a personal responsibility to deal with the threat himself, driven by a desire for justice or revenge. Grayson's decision could also stem from a fear of repercussions or a belief that the maniac would evade capture. Ultimately, he may have felt that taking matters into his own hands was the only way to ensure safety.