My brother in law recounts this story. Some acquaintance of his asked him how he would commit the perfect murder. He replied, thinking it an intellectual exercise, “I would buy an old shotgun from a pawn shop for cash, shoot the fellow and dump the shotgun far away in a large body of water.”
Later he found out the guy actually followed his advice, shotgun and all. Except he did it in front of 5 or 6 witnesses. I suppose stupidity is a hard obstacle to overcome.
Well, to hear some people tell it, as stupid as cops are it’s a damned good thing we have stupid criminals :-)
Truth is, most people who commit any crime, including murder, are not on the plus side of populations mean IQ. Your BIL’s story being a perfect example.
There are always those who think they are so far above the average intelligence of everyone else they can simply get away, literally, with murder. Thankfully they are in the minority.