Witnesses heard gunshots, then found him on the ground with a gunshot wound to the head.
Velazquez was one of six children. One of his sisters also died recently.
Family members say Velazquez was a hard worker who did not get into trouble.
"I want to know who is responsible for killing my brother and why. Why in cold blood? He wasn't doing anything wrong. He never left the house without us, his sisters or his parents, and was always with us working," said Nancy Velazquez, the victim's sister.
Chicago police have not made any arrests.
