Christopher Neely would drive for miles around Manhattan searching for his nephew, Jordan Neely, scanning bus stops and subway stations.

Jordan Neely, a former Michael Jackson impersonator with a history of mental illness, was homeless and adrift. His mother’s brother longed to offer him food, shelter or just a chance to freshen up. One day, Christopher Neely ran into Jordan on the subway. The younger man ran in the opposite direction.

“He has a place to stay but he doesn’t want to come home,” Christopher Neely told reporters. “That’s something my nephew told me.”

Only in death have Jordan Neely’s uncle and the rest of his family caught up with him. For five weeks, relatives and supporters have shown up daily at the manslaughter trial of Daniel Penny, a former Marine who choked Mr. Neely to death on an F train last year after he frightened passengers.

Christopher Neely and Andre Zachery, the victim’s father, have had to watch that moment, captured in harrowing video footage, over and over as Mr. Neely’s final struggles have been dissected. Mr. Zachery has often left the room rather than watch his son die onscreen yet again.

Their experience is a nightmare version of what thousands of families in New York City grapple with every day.