Joseph Paul Franklin terrorized the United States from 1977-1980. His feeling of inferiority and insecurities promoted the death of at least 20 people and 9 attempted murders. The total number of victims is unknown. During his 3 years of terror, he was given the name "the racist killer".

Sources:

https://youtu.be/ITgLiZGBjj4

https://www.fbi.gov/news/stories/serial-killers-part-4

https://www.wvpublic.org/radio/2020-06-25/june-25-1980-two-women-murdered-traveling-to-rainbow-gathering

https://murderpedia.org/male.F/f/franklin-joseph-confession.htm