Medicine isn't exact. Psychology isn't a science.

"Do we really need a reason? We are animals, killing is in our nature."

The quote is from a relatively new movie simply named "Pathology". It is about a pathologist that starts playing a game with other pathologists, a game where each of them kill someone random and the others must then figure out how it was done. Apparently (although this was not mentioned) one of the rules was that the cause of death has to be determinable (so no cremating after the murder). Spoilers.
The game went on for quite some time with the method always being determined (be it forced inhalation of liquid nitrogen or feeding nitric acid with booze, the methods were pretty unimaginative). Finally, the protagonist's fiancée came to town and the protagonist wished out of the game. Naturally, that was out of the question as he had already tasted the fruit and, as such, trapped by the game. So he decided to kill all the players. With so many targets (5) and a very limited time schedule (any death within the 'circle' would implicate the protagonist in the eyes of the remaining players, thus he would endanger himself and his fiancée), he had to take out everyone at once. He had to blow them up.
Sadly, he got sloppy. The one time it really mattered to be thorough, he got sloppy and did not make sure he got all of the targets. The 'dungeon master' survived, killed the protagonist's fiancée, after which the protagonist decided to carry out an autopsy on the DM... while the DM was still alive.

What bugged me was that out of the 5 other players, only 2 had a beef with him. One, who he slept with on multiple occasions, was killed by the DM shortly before the explosion. The other was the DM. The rest were unaware of the coitus or that the DM was going mad. By 'mad' I mean on a senseless killing spree. Stabbing many random people, without causing a genius mystery, without the mental thrill of outsmarting the others. Also, the DM was jealous over the protagonist due to the damsel he killed. So, the only person the protagonist really had to kill was the DM (as the damsel was already deceased) and call it quits. When two players die, it's rather easy to explain the wish to stop hanging out with people who kill each other, who are wildcards, who cannot be trusted to play the game objectively. The one thing the protagonist had to do is make sure the DM died. He didn't. Instead, he did the risky thing and hoped everyone was deceased, even though he was near the explosion. He refused to be methodical, he refused to be logical.

Overall, the movie hinged on the general assumption that pathologists, like fighter test pilots, have to be slightly mad, different from the general public by their thinking and distance from emotions. But what they appeared was rather different. They appeared to be like career soldiers, classic binary thinkers. Relatively unimaginative, always relying on simple steps, straight conclusions pertaining to only the current situation. No joy, no pain, like machines. The only satisfaction being the hope of being better than the rest, of making it further, of being the last man standing, of winning. For pathologists, especially for those who believe that what they find can benefit those who are still alive, such a game is rather illogical. People who have chosen their career to help people, who live in the hope that their work helps people, are not the people who would start cold-blooded murder circles, even if it is just for kicks.