Another police spokesman, Lieutenant Raymond Evers, said earlier in the day, that police were working with the family to determine if anything was missing from Walker's backpack and wallet, which were recovered at the scene of the killing.
On Saturday, Police Commissioner Charles H. Ramsey announced a $20,000 police reward for the arrest and conviction, as well as an additional $10,000 that was being offered by the Fraternal Order of Police Lodge 5. The FOP reward was increased today to $15,000 for the arrest of the suspect, Little said in a statement this morning.
The increase comes as police say the investigation has turned up little information.
"We don't have much at all. Our homicide investigators are really pressing to try to get some information, and leads, some evidence to see who this person is. Nothing as of yet," said Evers. "They are putting everything they have into it, but nothing has come in that is going to lead them to an arrest."
Police said they haven't ruled out whether more than one person was involved in the slaying.
Walker was in civilian clothes, walking west on Cecil B. Moore Avenue between 20th and 21st Streets when he was shot multiple times just before 6 o'clock Saturday morning. He was believed to be walking to catch a bus on his way home after completing his shift at 22nd Police District headquarters. He was apparently able to unholster his gun, which was found under his body at the scene. However, investigators do not believe he fired his weapon, Evers said.
The $20,000 reward for information in homicide cases is a new initiative for Philadelphia, announced in January. The reward, now offered as standard practice in all homicide cases, was hailed as "a game-changer" by Mayor Nutter at the time of its announcement.
Police continue to search for witnesses and informants in the investigation, and ask anyone with information to call 215-686-3334. Tips can also be sent anonymously through the www.phillypolice.com website.
"We're working with investigators, law enforcement officers in the area," Evers said. "We're going to put as much time and effort as needed to bring this job in."
Contact Jonathan Lai at 215-854-5151, firstname.lastname@example.org, or on Twitter @elaijuh.