LOS ANGELES (REUTER) - Police questioned two potential witnesses late on Monday in connection with the murder of entertainer Bill Cosby`s son, who was gunned down last week while changing a flat tire near a freeway. One of them reportedly fit a recently released composite sketch of a potential witness to Ennis Cosby`s murder, which took place early last Thursday on a darkened roadside in an affluent neighbourhood. A woman who saw part of the attack gave police a description of the killer as a white male wearing a knit cap, and that was used to put together a composite drawing released last weekend. Police said the man they sought was driving a blue hatchback vehicle. KCBS reported the two men being questioned on Monday were in a similar car. Ennis Cosby died from a single gunshot to the head. Investigators said robbery was the likely motive.