Diane, 54, was in the house when Bryan was shot multiple times by a heavyset man wearing a polo shirt.
She said that although homicide detectives came to the house after the slaying and have been in touch by phone, she has not seen them canvassing the neighborhood or following up on leads she said she gave them.
Cops have arrested or identified suspects in two of the six cases. The city has offered $20,000 rewards in each unsolved case, although other sources helped bring the reward in the cop's killing to $118,000 at last count.
The murder of Walker, 40, as he was walking on Cecil B. Moore Avenue to catch a bus after his overnight shift at the 22nd District, 17th Street and Montgomery Avenue, has spurred a public outcry.
Investigators have been working around the clock on the case. They have received numerous tips, conducted interviews and released surveillance videos of two men suspected in the shooting.
"Any time you lose someone that you know, it's going to take an emotional toll," Ramsey said. "We've had a lot of police officers that have died tragically . . . but we're not able to shut our doors mourning. . . . We all have to keep pushing forward."
A video released Monday shows two men on the south side of the 1900 block of Cecil B. Moore tailing Walker, who is on the north side. The video shows one then crossing over to Walker, near 20th Street. Police say that's where the robbery was announced and Walker was shot.
A second video, released Tuesday, shows a crisper image of the two suspects walking north on 19th Street toward Cecil B. Moore. One man, believed to be the gunman, is black, bald, possibly with a beard or goatee. He is wearing a light-hued, hooded sweatshirt and dark shorts.
The second man is also black. He wears a dark hooded sweatshirt and dark shorts.
Ramsey said Tuesday afternoon that funeral services tentatively were planned for Deliverance Evangelistic Church in North Philadelphia, with a wake Sunday and a service Monday.
The FBI and U.S. Marshals Service are assisting police in the investigation. Ramsey stressed that federal law-enforcement officers have already been helping out since June in the 22nd District, where Walker was shot, and in the 24th, 25th and 12th districts.
The other four homicides:
* 12:20 a.m. Friday: Idris Bilal, 19, of Master Street near 30th, shot on 29th Street near Oxford in Brewerytown. Killer at large.
* 2:15 a.m. Saturday: Dwayne Dixon, 22, of Darby, Delaware County, shot in a car on Girard Avenue near 49th Street in West Philadelphia. Killer at large.
* 3:40 a.m. Saturday, Edward Wilson, 23, shot on 63rd Street near Woodland Avenue in Southwest Philadelphia. Cops seeking a known suspect.
* 4:20 p.m. Sunday: Donald Mines, 20, shot on Wells Street near Loretto Avenue in Northeast Philadelphia. George Cobb, 25, arrested and charged with murder.
Contact Julie Shaw at 215-854-2592 or firstname.lastname@example.org. Follow her on Twitter @julieshawphilly.