Many people consider Carl Panzram to be the most vicious American serial killer. The 6-foot-tall, tattooed man with icy grey eyes operated as a solitary crime wave for over 20 years. He committed robberies, rapes, and murders in numerous cities across several nations. Despite being hanged at the age of 38, he admitted to more than 20 killings and the rape of up to 1,000 men and boys during that time, in addition to other crimes, including burglaries and arsons.

Source Materials:

https://allthatsinteresting.com/carl-panzram

https://criminalminds.fandom.com/wiki/Carl_Panzram

https://serialkillershop.com/blogs/true-crime/carl-panzram

https://the-line-up.com/carl-panzram

https://birthmoviesdeath.com/2012/04/01/carl-panzram-the-serial-killer-who-used-a-presidents-gun

Serial Killers: Shocking, Gripping True Crime Stories of the Most Evil Murderers by Brian Innes