Andy Anderson had been set to testify in the trial which begins this week, but was critically injured and declared brain-dead after a suspected hit and run. He died Saturday.
In reality, Anderson, 51, had been gone from his family for the last six months, said Kim Joyner, Anderson's little sister.
He had been hospitalized and unresponsive with extensive head and neck injuries - believed to be from a hit and run accident at Pine and Middle Belt in Inkster the night of Aug. 7.
"That's heartbreaking to know that he was lying in the street and no one was around there to help him," Joyner said. "I need closure for him. Because he can't do it anymore."
Anderson witnessed the murder of little 2-year-old Kamiya Gross also known as Kamiya French in July. He would have testified at this week's trial.
"To this day we don't have any answers as to what happened to him," Joyner said. "From day one up until now. And now he's gone and we still don't have answers."
Anderson had been in six hospitals and finally hospice - where he died. But his family still remembers a man full of life.
"He was doing his thing - walking and talking and singing and dancing just enjoying life, and his family -his daughter, his grandchildren," Joyner said. "And then this happens to him."
"Very active - walking everywhere, you couldn't stop him from going anywhere - he was walking," said Anderson's daughter Kimberly Anderson. "He was a good grandfather to my kids, definitely. He's a wonderful person."
Inkster police say all signs point to a hit and run accident. But they still do not know who is responsible for Andy Anderson's death.
"We've exhausted our leads - we are in need of some public assistance in this matter," Inkster Police Chief Vicki Yost. "If you see something, say something. A lot of crimes are solvable with the help and support of the community."
Andy's family said they are begging someone to come forward.
"I can't sleep at night knowing what happened to him," Joyner said. "How can you sleep at night knowing you did this to him?"
Anyone with any information should call Inkster police (313) 563-9850.
Those wishing to donate to the family's GoFundMe page to help with funeral costs may CLICK HERE.