Sammy McKnight, from Paducah, KY, was a burglar, pimp, and hustler in Harlem, NY. He was sometimes called "The Pimp" or "Pretty Boy." He was one of the two people most trusted by Malcolm Little (who later became known as Malcolm X); they lived in the same boarding house.
Sammy and Malcolm were partners in crime until a fight erupted between Malcolm and Sammy's girlfriend, and Sammy, with gun in hand, chased Malcolm down the street.
They later reconciled their differences somewhat, and in 1945, it was Sammy who called Malcolm Jarvis, Sr., [also know as "Shorty"] to come get his friend Malcolm Little out of New York. Shorty, a musician, lived in Boston. In New York, West Indian Archie had put a contract out on Malcolm Little because of a misunderstanding about a numbers hit.
After serving time in prison and becoming a member of the Nation of Islam, Malcolm X returned to New York in 1954; McKnight had died in the meantime.
For more see the "Sammy McKnight" entry in The Malcolm X Encyclopedia, edited by R. L. Jenkins; and The Other Malcolm, "Shorty" Jarvis, by M. Jarvis, et al.