https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1556-4029.2006.00273.x A study on this subject. Between 1970 and 2006 they were able to find a total of 90 healthcare professionals who were charged with medical murders. Not all were convicted. Modern Life Has Made It Easier for Serial Killers to Thrive Another good article. About 40% of murders are unsolved. The authors conclude that there are 2100 or so active serial killers in the US at any given time. So most of us are not out there killing people.