Real-world criminal science questions.

[Black Leviathan]

Ballistic pattern is pretty tough to stick as evidence because it's not as conclusive as the police want you to believe. A decent lawyer can either make it inadmissible or question it to the point of making it dubious to the jury. It's mostly to convince a jury that there's evidence where there isn't. It can show that a bullet was most likely fired by a specific type of weapon but unless your gun has a really irregular barrel the slug won't be conclusively tied to your weapon. What's really damming in an investigation is shell casings left behind. If you find slugs that match shell casings on the scene you can check the striking pattern on the firing pin or marks on the shell from the loading mechanism for any irregularity that will more conclusively prove it came for a specific gun.

But at the point where they have a slug and can ID the gun they can check against their probable suspects for anyone who has access to a gun of that caliber, and then the easier way to catch someone is hair or blood left on the scene or dirt or other organic debris in the suspects clothes that place them at the scene of the crime. That's usually sufficient to put someone behind bars.

[Black Leviathan]

Originally Posted by Polydamas

As others have said, probably the most important thing is how much attention the police give the crime. If a shooting or stabbing looks like just another gang killing, it may not get close attention, if it gets into the national media then it will get a full forensic treatment.

Outside of America shootings make a big splash and police take them pretty seriously because it could be part of an illegal arms investigation. There's a lot more resources brought to bear on a gang shooting in Mexico. Other countries don't have the civil protections the US has so police are more free to collect information and evidence.

Also shooting monsters that end up turning into humans when they die, especially if they have peculiar DNA because they're werewolves or Windigo, is a massive problem for chain of evidence. If there's a wounded human being on the ground and blood collected at the scene appears to have canine DNA markers it's going to make a mess out of the investigation. If you have a human body with a through-and-through bullet wound and dig a slug out of a nearby tree, but that human body was 9 feet tall and had three times as much muscle when it was shot then the forensics for that shooting then the crime scene is going to show a shooter that was at a different elevation and distance, if it can show that the slug matches the wound at all.

[Anaraxes]

Originally Posted by Black Leviathan

There's a lot more resources brought to bear on a gang shooting in Mexico.

The murder rate in Mexico is about 2-3x that of the US, with the murder-by-firearm rate being slightly higher (1-1.5x). Wikipedia tells me that the number of police in Mexico is about the same as the US (366 per 100,000 population, versus 391 per 100,000 in the US).

What extra resources did you have in mind?

[Polydamas]

Originally Posted by Black Leviathan

Outside of America shootings make a big splash and police take them pretty seriously because it could be part of an illegal arms investigation. There's a lot more resources brought to bear on a gang shooting in Mexico. Other countries don't have the civil protections the US has so police are more free to collect information and evidence.

My experience is Canada and the New Country in Europe. Like in most countries except the UK, China, and Japan, gangs can get firearms pretty easily (a handgun and a box of cartridges take up as much space as, what, a kilo of most drugs? and those come in by the tons ...) and something like the recent spree shooting running across the west of Canada get far more police attention than "a 19 year old male was found dead of gunshot wounds in an alley in Surrey, BC. Police say that the deceased was known to the police and investigations are ongoing" or a series of homeless people disappearing in a major metropolitan area.

[ericthered]

My wife and I like to watch crime documentaries together. We often remark that the way to not get caught with murder is:
1) Don't kill someone you know personally and have a motive to kill
2) Don't kill someone in a peaceful area
3) Don't kill someone considered "safe". This includes the wealthy, but it also includes the "upstanding", children, and police officers.

As a distant fourth, don't become a predictable killer.

Police investigations are incredibly expensive, and tied into local politics. An overworked department that sees multiple murders per year isn't going do doggedly follow every single one. If you avoid being one of the 10 most obvious suspects (by following #1), they might not bother to follow you. A lot of the documentaries we watch depict murderers who have killed before in a different jurisdiction that didn't track them down.

Police departments that cover small areas, don't see much crime, and have a less transient population can get attached to solving this one cold case and throw oodles of resources at it, because its a personal affront to their honor. You can get a similar effect if the case gets sensationalized, which can happen with category #3.

Most monster hunters won't cross those three lines on most missions. There are exceptions, of course, but most monsters won't be personally known to the hunters, won't be hunting in areas where the police are vigilant, and won't be a "Safe" Category. Exceptions to these rules do come up, but they are exceptions, and alarm bells should go off in players minds. For their part, GM's should use the exceptions sparingly, or be willing to relax police efforts.

[Fred Brackin]

It occurs to me that underlying all this is the assumption that dead "monsters" will never be recognized as monsters and will instead be treated as is they were ordinary humans who have been murdered for mysterious reasons.

There seem to be a lot of assumptions that would be required for the above to be true. Things like "The monsters don't kill each other or at least clean up after themselves with awesome efficiency." plus "The monsters don't kill a lot of humans and display the same clean-up behavior when they do.". This is sometimes attributed to conspiratorialy powerful vampires but seems unlikely for werewolves or zombies.

Also that there aren't a lot of monsters and even fewer monster hunters so as to make the whole thing easier to hide.

Then there is the whole thing of "The authorities don't know a _lot_ of things the PCs do." and you have to wonder "Why?".

I tend to think that the monsters can't be hidden that well and cases that can be described as "Multiple young males associated with gang activity found dead, naked and full of silver bullets." will get buried even faster than their bodies do.

[Flyndaran]

It is a major genre point for the public at large to be exceptionally blind to the supernatural dangers all around. And/or for the authorities to be actively covering up for some nefarious reason or the classic, "for their own good".

[AlexanderHowl]

Well, the majority of intelligent monsters will have human servants, who should probably be competent enough to get in the way of hunters. A vampire might have a blood cult devoted to them, a werewolf might have an extended clan that protects their own, etc. With their high point values, the human minions of monsters can be surprisingly competent and, since they are human, the authorities may care when they die.

For example, a local vampire has a blood cult made up of the wives and daughters of local leaders. If the hunters shoot and kill the daughter of the mayor or the wife of the police chief, they will be up to their eyeballs in grief. I doubt that they will be brought in alive.

[ericthered]

Originally Posted by AlexanderHowl

For example, a local vampire has a blood cult made up of the wives and daughters of local leaders. If the hunters shoot and kill the daughter of the mayor or the wife of the police chief, they will be up to their eyeballs in grief. I doubt that they will be brought in alive.

It depends if you're playing the situation as anti-player or as pro-vampire. Wives and Daughters of local leaders are valuable pawns, and the vampire didn't get possession of them by chance. Its not going to use them as expendable muscle. They're either part of a larger plot, part of the vampire's lifestyle, or useful hostages (which aren't useful unless they're announced). Only the most trigger happy PC's will shoot them without knowing their identity and the potential consequences.

If the PC's are traveling from place to place, having THAT city mad at them isn't too big of a deal. If they're only in one community, there aren't that many people who can act in that matter, and they have the leverage (and plot spotlight time) to cure or work around the problem. If every vampire above a certain strength has integrated himself into the local power system, that says something about the way your setting works, and also something about the way your secret works.

[The Colonel]

Originally Posted by ericthered

It depends if you're playing the situation as anti-player or as pro-vampire. Wives and Daughters of local leaders are valuable pawns, and the vampire didn't get possession of them by chance. Its not going to use them as expendable muscle. They're either part of a larger plot, part of the vampire's lifestyle, or useful hostages (which aren't useful unless they're announced). Only the most trigger happy PC's will shoot them without knowing their identity and the potential consequences.

Ideally in any campaign that pretends to realism the PCs won't shoot anyone without knowing their identity and potential consequences - unless they have been attacked themselves. It's a switch in mindset that some people don't seem to be able to make if they're over habituated to fRPGs. In real life the police get investigated when they shoot people, and even the military are having to start to worry about their actions being second guessed by civilians so vigilante PCs should definitely worry.
Some gaps in stringency are probably acceptable - many forms of monster may vanish down a masquerade based memory hole once the autopsy notes are reviewed - but human on human violence should be less so. Unless, of course, the party want to play a sort of van Helsing meets Starkweather campaign...