One Halloween in the Bronx, teenagers threw eggs at a car. The eggs probably cost the boys a few dollars. They cost Karl Jackson his life.

The year was 1998. Mr. Jackson and his girlfriend were picking up her 9-year-old son from a children’s party. Mr. Jackson had turned 21 weeks earlier. He was a quiet young man, the son of a nurse and a postal worker. He usually avoided going out on Halloween, not because he was too busy  he was a data entry clerk at Morgan Stanley  but because he thought it was too dangerous.

The teenagers’ eggs struck their car. Mr. Jackson stepped out of the vehicle. An argument began. Mr. Jackson had sat back down in the passenger seat when one of the teenagers pulled out a gun. A single shot rang out, striking Mr. Jackson in the head, killing him.

“I think it took us two years to even talk about it,” said Gloria Jackson, 62, Mr. Jackson’s mother. “We were just devastated. We never thought that anyone from our family would be murdered, especially on a holiday, for something stupid.”