Britain's most prolific serial killer was a Medical Doctor with a hypodermic needle; 200 plus as far as we know about! Lagopus.....
Dr. Harold Shipman-- convicted of 15 murders but known to have killed at least 250 patients. It is estimated that he may have killed as many as 459 patients, many of whom were cremated and couldn't be autopsied.
http://disturbinghorror.com/Serial-Killers/Serial-Killers-Bio/Harold-Shipman-serial-killer.htmlStrange that the anti-gunners in Britain didn't call for registration, bans, and burdensome storage requirements for hypodermic needles.