Maria has a rather dodgy relationship with the police in general. Technically, vigilantism is illegal, and what Maria does is murder in the eyes of the law. On the other hand, she never leaves identifiable DNA behind (she’s not even sure she has DNA, or finger prints, being so bizarrely structured), and the best cause of death they can find are “mysterious causes” (not even a heart attack, they just stop) and there’re more than a few police willing to turn the other cheek when murderers and rapists turn up dead. (there may also be issues based on how much the police know about the supernatural, if they know some of the criminals have super powers, they might be more accepting when they show up dead… although, I’m assuming super powers must be at least fairly well known, on account of me flying around with great big wings)
The real problem comes when someone turns up dead and the police can’t link them to anything. This happens when dealing with some of the careful demons, who possess seemingly normal people (for bonus fun, killing people may not kill demons in them, so my touch of death might not completely nerf returning villains, yay!).