Solving Chester homicides, even those committed in front of witnesses, has been difficult for law enforcement personnel, who often encounter a "don't snitch" culture.
Eleven of the city's 21 homicides committed in 2011 remain unsolved; 20 of the 24 killings of 2010 are still open, according to the state's uniform crime reporting system.
"We are here to make it a little safer for you," Whelan said while stepping into Jasmine Nails & Spa on Edgmont Avenue and catching the customers and workers by surprise.
"This is what we need," said regular customer April Womack, 30, of Brookhaven. "There is a lot of violence in this area."
Since the end of March, Whelan and company have visited five other neighborhoods in Chester. He plans similar walks in Darby Borough, Yeadon, Collingdale, and Colwyn this year.
"It is such a great learning experience for us," Whelan said. "It makes us more driven to take a bite out of violence."
On one of the walks, to the Sun Village neighborhood near Ninth Street and Elsinore Place, neighbors told Whelan they sleep in their basements because they are afraid of being shot. Bullets fly through the walls of new houses; the older brick buildings that once housed the families of Sun Ship workers are more secure, he said.
Gunfire was also a concern Monday night.
Victor Dick, 84, of the 2100 block of Madison Street, gave Whelan and Ryan an earful from his front porch.
"You should have heard the 9mm discharged last week," he said. He counted nine shots. "Did you hear about our robberies? We've had three of them."
Dick, a retired auto mechanic, has lived in Chester for 46 years with his wife, Theresa, also 84. The two are scraping by on a fixed income. "I wish I had what they spend on ammo; I could live a bit better," he said.
The group, which included assistant district attorneys, investigators, church leaders, and volunteers from the Chester Community Improvement Project, made its way along Crosby Street.
Whelan took a football and let it fly to a teenage receiver waiting down the street. The pigskin sailed up into an overhead wire, fell, and bounced off a car hood.
Whelan asked to try again but didn't get a chance. The teens threw the ball back and forth, bypassing him.
Older residents seemed to welcome the visitors, but young adults were not as accepting.
Brandon Johnson, 18, one of those playing football, said that although Whelan had an acceptable throw, he was "kind of getting in the way" of their fun.
A group of teens sitting on the curb at 21st Street seemed more interested in the weapon Ryan had on his belt than in listening to the pitch to call authorities.
"We are really tired of coming down here and picking up young people," Ryan told the skeptical group.
"I just don't want to be labeled a snitch," said Wahfe Grange, 19. "That is just how it goes."
Fifteen-year-old Karissa Staples doesn't think teens would be up for being witnesses in court because of possible retaliation. But she hopes someone steps forward and gives police information on a recent murder.
"They just killed my brother. He was 23," she said.
Her brother, Jabril Williams, was walking from his aunt's home near 21st Street and Edgmont on July 7 when he was killed. "Got shot at five and died at seven," Staples said.
A lime-green poster bearing R.I.P. condolences is shrink-wrapped to a phone pole at the scene where Williams was shot. Stuffed animals, baseball caps, and candles are undisturbed at the base of the pole.
Williams was trying to make a change in his life and step away from trouble, Staples said.
"Stop the violence, increase the peace," she added quietly.
Contact Mari A. Schaefer at 610-892-9149, firstname.lastname@example.org, or follow @MariSchaefer on Twitter.
To contact Chester City detectives, call 610-447-7908, or call county detectives at 610-891-4700.