Someone stopped by searching for “what percentage of americans are murderers.”
If you assume that all murderers kill only one person, the percentage would be approximately 1 in 22,250 or about 0.000048 percent. So that puts our upper limit at 48 in a million for 2011.
However, we know that many murderers are multiple murderers? What percentage? That is less clear.
As you can see from the FBI graphic on the left, only two out of three murders are “solved by arrest.” So one third of murders are never solved. We know that a substantial percentage of killers will kill again, but the percentage of “cold cases” is so high we have no clue to what percentage of the unsolved murders were committed by one time killers. When a cold case is solved, it is common to discover a string of victims, murdered over a number of years.
The little and sketchy information I have indicates that about 8,000 Americans killed someone in 2009, and the “murderer rate” is close to 2.6 per 100,000 population. But of course, without much more data than we have, any guess at the percentage of Americans who have deliberately killed someone is a guess.
So where does that leave us? Actually, almost up that proverbial creek without a paddle. But running the data we have through Bayesian analysis gives us ‘high confidence’ that less than one American in 2500 will kill someone during their lifetime.
Most of those killers will be engaged in criminal activity; and most of their victims will be either partners in crime or rivals in crime.