William Suff , also known as the Riverside Prostitute Killer and the Lake Elsinore Killer, is an American serial killer.

In 1974, a Texas jury convicted Suff and his then-wife, Teryl, of beating their two-month-old daughter to death. The Texas Court of Criminal Appeals later reversed Teryl’s conviction but upheld Suff's in Suff v. State (Tex. 1976) 531 S.W.2d 814, finding insufficient evidence to convict her as either the primary actor or a principal in their baby's murder. Though Suff was sentenced to 70 years in a Texas prison, he served only 10 years before his 1984 release on parole.

He subsequently raped, stabbed, strangled, and sometimes mutilated 12 or more prostitutes in Riverside County, beginning in 1986. On January 9, 1992, Suff was arrested after a routine traffic stop.

Described as a mild-mannered loner, Suff worked as a county stock clerk who allegedly delivered supplies to the task force investigating his killing spree. He liked to impersonate police officers and cooked chili at office picnics. In fact, it was alleged that he used the breast of one of his victims in his chili, which won the "Riverside County Employee Chili Cookoff." He was also working on a book about wild, lethal dogs. He enjoyed vanity plates and was an avid volunteer in the county's car-pooling program.

Eight page (all pages front and back equaling sixteen pages total) handwritten letter on stationary sized paper. Letter is general content and is signed Bill. Original matching envelope is included.