Reginald Vernon Oates was born in 1950 in Baltimore, Maryland, and was adopted at an early age by the Oates couple. Growing up in an urban area, he faced segregation and social disadvantages, often being attacked by his peers. In 1965, while in the 9th grade, Oates was accused of attempting to rob another student at gunpoint for a few cents. He denied the accusation but was found guilty and sentenced to two years in a juvenile detention center. During his incarceration, Oates suffered physical and sexual abuse, which left him deeply traumatized. After his release, he returned to his adoptive parents, dropped out of school, and found work as a waste collector. He converted to Christianity but began exhibiting signs of mental illness.

On April 17, 1968, Oates lured 10-year-old Lewis Hill into Gwynns Falls Leakin Park, where he beat and raped him. Afterward, he slit Hill's throat, violated his corpse, and mutilated the body by removing the head and hands. The following day, he used the same tactic to lure three more boys: 8-year-old Larry Jefferson, his 5-year-old brother Mack, and 10-year-old Lester Watson. He beat and stabbed all three, sexually assaulted their bodies, and mutilated them, taking their genitals with him. On April 19, authorities discovered the bodies and arrested Oates, who was found carrying the murder weapons and body parts.

Following his arrest, Oates was charged with four counts of murder, rape, two assaults with intent to rape, and one armed robbery. He pleaded not guilty by reason of insanity. Psychiatric evaluations concluded that he was mentally unfit to stand trial. In November 1968, he was committed to the Clifton T. Perkins State Hospital in Jessup, Maryland, for compulsory treatment.