Actually still 19 most unusual for a healthy looking person that, you have to at least consider drugs being a cause, first place to look and I'm sure the ME looks that way at autopsy, first thing to check.
It's like a middle-aged married woman gets murdered, the automatic prime suspect is always the husband, especially if there is a death insurance policy ( I don't call it life insurance, it's really death insurance ), or maybe marital issues leading to a divorce and the guy doesn't want to give up half his assets. Not very many people get whacked for no reason whatsoever, maybe a rapist does that to eliminate a potential witness, but in general it's over money. I watch a lot of of those crime shows on the Justice network mainly because it's one of the few channels I can reliabilly pull in with with crappy indoor TV antenna and it's not all pixelated.
Police have so many tools to work with these days, you don't stand much of a chance being a career criminal, they can figure it out if they want to in most cases. They may ignore it something like the murder of a prostitute, but if it was the mayor's daughter that got, raped and murdered, it's a different story