Walker was last seen at the Martin Luther King Jr. Towers playground located at 113th Street and Lenox Avenue in New York City, New York on August 10, 1989. He was accompanied by his mother, who gave him permission to play with two other children while she sat on a bench. A man approached her and began a conversation with her, and Walker's mother became distracted. When she turned back to look for her son, he was gone. The two children who were playing with him, a ten-year-old girl and her five-year-old brother, were missing too. The two children re-entered the park through a hole in the fence a short time later. They told Walker's mother they'd left him in the park. The police questioned the children extensively, and also interviewed the man who spoke to Walker's mother. They looked into the possibility that Walker was taken by a member of his own family, but concluded he had probably been abducted by a non-relative. He has never been heard from again.

Walker's case shares striking similiaries with the disappearance of Christopher Dansby, who disappeared from the same playground in May 1989, three months before Walker did. Both boys were African-American toddlers and lived in the same apartment building. Both disappeared on the same day of the week (Thursday) at roughly the same time (Walker at 5:00 p.m., Dansby at 7:00 p.m.) In addition, just before his disappearance, Dansby was playing the same two children who were with Walker when he was last seen. Police still aren't sure whether the cases are related, however.

Authorities investigated the possibility that the boys' cases were connected to a black market baby-ring operation and that the infants Andre Bryant, who was abducted from Brooklyn in March 1989, and Carlina White, who was taken from Harlem in August 1987, were other victims. All of the children are African-American.

Walker's parents both still live in the same neighborhood he disappeared from, and his mother hopes he is still alive and will return to her. His case remains unsolved.