Killing a random stranger and getting away with it would be pretty easy. Sure, go ahead and do stuff like burn your clothes and throw away the murder weapon, but that’s just insurance because there are no leads for the cops to trace back to you. This is the reason serial killers can kill over and over and over again.
In most murders there isn’t much of an investigation, because either the perpetrator is obvious, or there aren’t any leads.
Thanks to all the Breaking Bad I’ve watched, I know that Ricin is an effective poison that, unless it is looked for, will probably go undetected. It will basically make it look like the victim had a heart attack. Of course, if the victim is an otherwise healthy person, and the autopsy shows there was no underlying cardiac condition, they might start to investigate further…
So in that case we bring out our old friend, hydrofluoric acid. Get a nice HDPE hazmat suit with appropriate chemical respirator, a big HDPE barrel, and a butt load of hydrofluoric acid. Put victim in barrel, put acid in barrel, let stew for a couple days…even if it gets found, it will be nearly impossible to even identify the victim, let alone what little trace forensic evidence you might have left. The biggest problem is buying the mass quantities of acid and not getting found out through that…best get a good cover as either a high school chemistry teacher, or owner of a chicken franchise that itself is owned by a large, German industrial company that itself is just a shell/front.
Whatever happened to good old blowing up the victim’s boat?
I decided several years ago that the most effective way to commit murder was to get Jack Bauer really pissed off at someone.
That’s a perfect suicide.
Get two tickets to a cruise, next-door cabins. Send one of them to your victim, and the other to Jessica Fletcher.
I’m not seeing how.
Getting Jack Bauer pissed off?
At someone else. How would that be suicide?
How do you know he isn’t going to get pissed off at you instead? The guy’s a loose cannon!
I see, yes.
Problem is, if you want to kill someone you by definition have a motive, even if it’s not obvious.
The perfect crime has no motive; it would have to be the senseless random killing of a complete stranger.
In gangster movies it seems to be the custom to leave the murder weapon with the body. I assume that ensures it can’t be found in your possession after the event, and taking it somewhere to dump it is just another place to be seen.
Especially if there are cannoli involved. 
This is all pretty bad advice.
(1) Never take the body with you. You can’t explain a dead body, and there’s always a chance of being seen, getting pulled over, or even simply getting in a car accident.
(2) Don’t carry the weapon with you. If you are found with it you are toast.
If it were me, I’d start regularly taking walks in my neighborhood late at night, around midnight or so. Find a single, female, elderly neighbor, and figure out how to break into her house. Buy a generic knife, use it to stab her, and then leave it at the scene. Do obvious things like wear gloves, long sleeve pants and shirt, and a hat/something on my head. I shouldn’t leave any DNA or fingerprints, and even if I did, the cops don’t have anything to match them against.
I’ve watched a lot of the first 48, and convictions almost always happen because the criminal is retarded. They do one or more of the following:
(1) Commit the murder in front of cameras or witnesses
(2) Murder someone they know
(3) Get caught with some damning evidence. Blood spatter, the weapon, the dude’s wallet, or something that can’t be explained.
(4) Leave fingerprints at the crime scene
(5) Confess
First, wait 80 years…
I see there is no mention yet in this thread of Edmond Locard, French crime investigator circa 1900-1910 or so, for whom the “Locard Principle” is named: Every contact leaves a trace.
I think I’ve seen this written as something along the lines of:
“Every criminal leaves something behind, and takes something away with him”
That could mean blood, hairs, clothing fibers, footprints, mud on your shoes (Sherlock Holmes was famous for mud on the shoes analysis), etc.
http://www.forensic-medecine.info/criminalistics.html
http://www.drtomoconnor.com/3220/3210lect01b.htm
(Those two Wikipedia articles are just brief stubs.)
Or, to find more, just google for: Every contact leaves a trace Locard
Find a situation where a schizophrenic is in a close proximity to your intended victim on a regular basis. Say, perhaps, a panhandler in the subway station he uses daily to commute to work. Then, as you pass the panhandler, throw a few dog biscuits in his money bowl, in plain view of the small, hungry dog you’re carrying. Then, as the train approaches and your intended victim waits precariously by the track edge, while you are a good distance past the panhandler in some discreet alcove, release your dog to sate his appetite. Your dog, of course, has a speaker built in to his collar, and you hold the wireless microphone. As your dog retrieves the doggie treats from the bowl and begins to munch, looking very much like he’s talking, you speak into the microphone, *“see that guy over there with the black briefcase and bowler hat?”…”yeah, what about him?”…”he’s satan, push him onto the tracks in front of the train and rid the world of evil.”
*
As the carnage ensues and disorder commences, you scoop up your pup and walk discreetly away. Not much in the police report will link you to the crime: *“subway schizo claims poodle told him to do it.”
*Easy peasy, nice and easy.
Tibbytoes, I can’t think of a single thing that could go wrong in that scenario. It’s perfect!
No, no, no.
The problem is, you’re tied to the vat of HF. It’s not easy to get. When the cops find the vat of acid, they’re going to trace it to you.
You absolutely cannot have a connection to the crime scene. How do you transport the HF and so on to where you’re dissolving the victim? How do you transport the victim to the scene? How do you do all this without leaving traces of the victim and HF all over your car and person, and without leaving a record?
We are discussing a perfect crime here, right? Which means all this talk about disposing of the body or the murder weapon is foolishness. If you can’t leave the murder weapon at the crime scene, then it’s not a perfect murder weapon. If you have to transport the victim, or the victim’s body, that’s not a perfect murder.
Think, people! It’s like I’m dealing with amatuers here!