On Oct. 21, 1960, as “West Side Story” was playing on Broadway, a real blood feud was playing out at a youth dance and on the streets of Spanish Harlem between two rival gangs called the Viceroys and the Dragons.

About 8 p.m. that night, William M. Jenkins, 18, was shot through the stomach and back, rendering him a paraplegic. He continued his life of crime, however, becoming known to the police as Wheelchair Willie, while two teenage brothers in the Dragons were arrested and imprisoned for shooting him.

“West Side Story” popped up again on Broadway last month, and, 49 years after it happened, so did the case of the Jenkins shooting. After Mr. Jenkins died on March 13 at age 66, the city medical examiner’s office ruled his death a homicide due to infectious complications caused by the gunshot wounds, making it the oldest reclassified homicide in New York Police Department history.

Samuel Jenkins (L), William Jenkins (R)

“I can’t believe this,” one of the brothers, George Lemus, now 64, said after he was told the news Wednesday at the computer repair business he runs in Midtown Manhattan. A little while later, he looked down at his arm. “The hair stood up,” he said, holding out the arm, still fresh with goose bumps.

Mr. Lemus’s brother, Robert, died a decade ago at age 58. The shooting haunted him until his death, said his son, Robert Lemus 3rd: “He lived with a level of remorse for the fact that, at his hands, someone had a handicap his entire life over an evening of probable misunderstanding.”

The district attorney’s office said it would not prosecute because the brothers had already served time (Mr. Lemus said he was imprisoned for a year and half and his brother for five years) for the shooting and because witnesses and medical records would be hard to come by, the police official said.

The victim’s brother, Samuel A. Jenkins, even questioned how his brother’s death could be attributed to long-ago violence rather than the myriad medical problems he endured in his life or the recent acute deterioration of his health.

When asked about the Lemus brothers, he said that his family held no grudge: “Willie forgave them and I forgive them, if they are still alive.”

There’s a lot of personal history better off forgotten.