One finally did - a 30-year-old man from Delaware County who had seen the fleeing vehicle but not the crash near Arbor Lea Road.
Chitwood said that man - whom he declined to identify - called police.
Patterson had died instantly. Chitwood said homicide and accident investigation detectives have been working around the clock to find the driver of the car that hit the married father of three grown children.
They released a video of the car as it "flew through" the intersection of Providence and Springfield Road moments before the crash, he said.
After the car hit Patterson, it sped away - dragging its front bumper - east on Providence, left onto Lansdowne Avenue, and then right onto Lincoln Avenue in Yeadon, Chitwood said.
Shattered pieces of the bumper and a front headlight left behind will give police clues to the make and model of the car. Auto-body shops have been contacted to be on the lookout for a car with front-end damage.
Surveillance video collected along the route the car traveled before and after the crash will be mined for evidence.
"It's like a puzzle," said Chitwood.
The department has received 60 calls, Facebook posts, Tweets and e-mails with information, he said.
The family has declined to talk to reporters.
Patterson was known as the neighborhood dog walker. He and Baby were out three or four times a day chatting with friends and strangers, Chitwood said.
On Sunday, Baby had escaped from Patterson's backyard. Police theorize Patterson found the dog, put her on a leash, and was crossing Providence Road to return to his house on Carriage Lane when the crash occurred. He was about a block from home.
He had been married to his wife, Barbara, for about 48 years, said Chitwood. The family moved to the neighborhood about 15 years ago from Birchwood Road in Aldan - less than a mile from the current address.
"He was a tremendous guy - so helpful and kind," said Lynne Leonardo, who lived next to the couple on Birchwood Road. "It is hard to even put it together," she said, shaking her head.
Bob Schwindt, 72, a neighbor from Birchwood, said Patterson was a "super nice guy" who would always lend a hand. He recalled how Patterson helped him build a shed and put up doors in his house.
"He was always there when you needed him for something," said Schwindt.