I'm a big horror fan, but somehting i've been thinking of lately is how the police is most movies are useless, of course thats mostly because either the situation is of supernatural nature or because the script wants them to die to show how the villain is evil and unstoppable. So, i was wondering what real law enforcement would do in these situations. Anyway, here's a few of them (i will limit the list to scenarios that kinda could happen IRL, so i'm excluding supernatural shit).

1. Friday the 13th-type scenario: A small town wich has a camp on it and local legend says that anyone who tries to camp there or visit the lake at night will be attacked by a serial killer. Teenagers and college kids have been going there for years, and they end up either dead or missing, with only a handful of survivors. After the 5th movie, Jason is given supernatural powers, but in this case i'm basing myself on the 1-4 and remake versions of Jason, just a very resistent, tall (around 6'5), strong guy with amazing hunting and survivalism skills and fucked up in the head (he might also be mentally challeged).
2. Halloween-type scenario: A serial killer visits a small town during Halloween (not every Halloween, the movies in the original timeline shows that Michael Myers is very irregular, attacking in '78-'81-'88-'89-'95). He has one target, and every death is basicly due to killing anyone who he sees as a threat to his objective (to a point that if his target moves across the country he will follow it). Also, as Halloween is over, he's gone. Again, after the 4th supernatural elements are introduced, but i'm using the 1-2, remake, Old Man Michael, and Lauren Strode timelines versions, just a guy who is tall (around 6'3), strong and is a master at stealth and a psychopath.
3. Saw-type scenario: A serial killer who kills his victims by putting them into deadly games where they need to escape traps in order to survive. He has the knowledge and resorces to make any trap he wants, and he also has the help of a cult of followers that will continue his work in case he dies or is captured by the police. He is a master estrategist and if very often several steps ahead of anyone, even his disciples. And on top of that they have infiltrated the local police where you work at.

Feel free to answer just one, or all of them, whatever you want. I'm really curious to read the answers of real life policemen. Also, i'm in the US, around the SF Bay Area, but people from other countries are welcome to answer as well!