Who killed Reggie in “The Last Days of Ptolemy Grey”?

In "The Last Days of Ptolemy Grey" by Walter Mosley, Reggie's death is a traumatic event that sets the novel's plot in motion. Ptolemy Grey, the novel's protagonist, is an elderly man suffering from dementia who is living in squalor in his Los Angeles apartment. He receives a visit from his grand-nephew, Reggie, who tells him that he is dying of cancer and asks for Ptolemy's help in securing a $10,000 loan from a local criminal named Melinda.

Reggie's death in a drive-by shooting leaves Ptolemy devastated and questioning his own purpose in life. As he struggles to make sense of what has happened, he begins to experience vivid hallucinations and memory flashes from his past, including his time as a young man in the Navy and his involvement with a woman named Robyn, whom he loved deeply.

Throughout the novel, Ptolemy is plagued by a sense of guilt and regret over his past actions, which he believes may have contributed to Reggie's death. His attempts to uncover the truth about Reggie's murder lead him to Alfred, a member of the criminal underworld who reveals the shocking details of Reggie's demise.

As Ptolemy grapples with the truth about Reggie's death, he also confronts the harsh realities of his own life. He comes to realize that he has been neglected and taken advantage of by his own family and that his own past mistakes have left him with little to show for his long life. In the end, Ptolemy's journey is one of self-discovery and redemption, as he seeks to make amends for his past and find a sense of purpose and meaning in his final days.