From there, for now, the trail goes cold.
The viciousness and apparent randomness of the killing of Amber Long jolted city residents - a young woman with such promise, dead in her mother's arms.
Long, 26, an architect originally from Williamsport, Pa., chose Philadelphia as a place to plan a future. She had worked at the company that designed the nearly completed townhouses on the street where she died Jan. 19.
The case was assigned to homicide's Special Investigations Unit, which is headed by Lt. Mark Deegan.
More than a month later, police say they are making progress in the case, tracking her killers' getaway path and ruling out two men who ended up with Stephanie Long's stolen phone. They are doggedly pursuing leads. Getting closer.
"But progress in this line of work," Deegan said, "means pointing to someone and saying, 'They did it.' "
And that's something police can't do yet.
Each piece of evidence unearthed so far has been as vexing as it has been valuable.
There's a video of the killing - but the killers' faces cannot be seen. There's a clear image of the car on video - but the tag number is not visible. Thanks to enhanced footage from the FBI, there's now a shot of a man who investigators believe is the triggerman, sitting in the backseat of the Impala. But his features are blurred.
There's the crime itself. Detectives say crimes of this nature can often be clearly divided into two categories: purse snatching and gunpoint robberies. In this case, what started as a purse snatching turned into something deadly.
"Usually people don't try to steal a purse, and when there's resistance, shoot the person," Deegan said. "It complicates matters: Are we looking for a purse snatcher or an armed robber?"
And then there's the setting of the crime.
On the whole, Northern Liberties is a patchwork of busy side streets, crowded music venues, and trendy bars. Front Street is different.
Front Street is barren. Long died near a gated apartment complex, a cluster of as-yet-uninhabited townhouses, and not much else.
A year from now, the street will probably be bustling, but right now there aren't many doors for detectives to knock on - or potential witnesses to call in.
Investigators were set back for about 24 hours the day after Long's killing when a man called in a false tip to frame acquaintances over a drug debt. He's now facing charges of lying to police.
The homicide unit tip line has stopped ringing lately despite a $37,000 reward offered in the case, Deegan said. (Anyone with information about the case is asked to call the homicide unit at 215-686-3334.)
Police believe the gunman and his two accomplices had driven into an isolated section of Northern Liberties looking for an easy score. So while in many homicide investigations police pound the streets and clear corners to flush out suspects, in this neighborhood, there simply isn't anyone to flush out.
What's left is a time-consuming set of tasks for investigators: reconstructing blocks and blocks worth of surveillance footage, awaiting cellphone records, DNA results, and possible ballistics matches, and canvassing rental car companies in search of records that might lead them to the Impala.
"It's a slow, methodical process," Deegan said, sitting among the stacks of files in the homicide unit. "We're pretty good when we rely on ourselves, but we're not just relying on ourselves."
More information from car companies, DNA testing, and phone records is slowly coming into the office. In the meantime, some recent leads have surfaced that police say could prove decisive.
Through cellphone records, detectives knew someone had turned on Stephanie Long's phone - stolen with her purse in the attack - near Broad and Girard the morning after the killing.
The records led investigators to a Kensington beer shop. The cellphone had apparently made its way onto the cellphone black market, Deegan said. A man at the shop said he had bought the phone from another man, and that man told investigators he was the one who found it near 12th and Girard.
"We had them in here for quite a while, both of them," Deegan said, "and we don't think either of them are involved, or know the killers."
Though the cellphone was a dead end, it did provide investigators with an idea of where the car was in the minutes after Long's death.
"We think the car gets up there quick and they want to get rid of anything that associates them with that scene," Deegan said.
Now, Deegan added, investigators can go about tracking the car from that point onward - in the hopes that traffic cameras or private surveillance may have caught a glimpse of the tag.
And the killers' path itself provides potential clues.
They bypassed major roads like I-95, Columbus Avenue, and Broad Street, and instead turned onto 12th Street, leading detectives to believe that they may have been familiar with the area.
"That's why we're concentrating on that North Philadelphia area, because they didn't keep fleeing," lead detective John McNamee said. "Those people who live in that area - even if they don't think it's significant or important - they need to call and tell us what they think they saw."
Detectives are confident the tip line will start ringing again. It always does.
Someone with knowledge of the crime will get arrested and try to cut a deal. Or the image of Amber Long dying on a sidewalk in her mother's arms will gnaw at the conscience of someone close to her killers. Or someone will simply decide he or she could use a $37,000 payday.
"People talk," Deegan said. "People talk."