Nearly 200 people showed up. Police believe at least 30 were still in the vicinity afterward when someone opened fire after Amaker, Bailey, and another friend climbed into their car.
That's why police figure someone must have seen the gunmen approaching the corner. Someone must have seen them shoot into the car, killing Amaker and Bailey and wounding their friend.
Someone must have watched as another friend jumped into the car, pushed an unresponsive Amaker out of the driver's seat and sped off to Lankenau Hospital. Someone must have seen what the killers looked like, or what they were wearing, or which way they went when they fled.
But it has been nearly three months since Basir Amaker and Karon Bailey were killed, and not a single witness has come forward.
Amaker's mother, Suenee Walker, was determined to keep her only child off the streets. That's why she didn't mind when he brought friends to their home in Overbrook to play video games, hanging out for hours on end and eating takeout pizza. Sometimes Green and Bailey came over, too, holing up in Amaker's bedroom.
"With all these shootings and killings, at least they were in the house," she said.
Amaker's father has a long criminal past and was estranged from the family. Walker saw a different path for her son, a class clown with an artistic bent.
Two months before his death, he started a job with the U.S. Postal Service. Excited, he texted his aunt Amira Amaker a picture of his new ID card on his first day on the job.
Amaker was supposed to grow up, have children, carry the family name, his aunt said.
"I don't think they know what they took from us," she said.
Bailey, one of 11 siblings, was a homebody, too, and particularly close with older brother Marquise Stevens. He loved to take photos, to spend hours editing snapshots on his iPad, to play basketball by himself in a pair of Chuck Taylors at the neighborhood park.
"He was a family person more than anything," Stevens, 29, said. "He made all of us closer."
An uncle in the Air Force had inspired Bailey to enlist. He failed the entrance exam but was studying hard for a second try. His mother, Monica Bailey, remembers him laboring over practice tests, correcting himself, and starting over again.
"He wasn't one to stand on the corner or go to the bar," she said. "He was so focused on what he had to do in life."
Both friends had been shocked by Green's death.
"Basir came to the house that day and banged on the door - constant banging," Stevens said. "I saw from his face something was wrong."
Amaker and Bailey's homicides were the sixth and seventh of the new year, coming at the end of a violent week.
And with no witnesses and no leads beyond a few nicknames, solving the double murder is daunting, said the Homicide Unit detective assigned to the case, Ed Tolliver.
There's no description of the killers. Police have no idea where they came from or how they left. The 911 calls from the scene simply reported the sound of gunshots.
A motive is still unclear - Amaker and Bailey didn't have any known enemies and weren't involved in drugs or gang activity, Tolliver said. Both had clean records.
The friend who went to the memorial with Amaker and Bailey - who was sitting in the backseat of the Honda during the shooting and who was hit in the legs - told police he didn't see anything and couldn't describe the gunmen.
Police aren't even sure exactly how many people were involved in the shooting. Ballistics evidence shows at least two guns - large caliber and small caliber - were used.
But without a witness, without a description, the trail has gone cold.
"We have no tip calls, nothing," Tolliver said.
He's not sure why no one has called in.
"It's just unusual," said. "Someone always talks."
In the meantime, the men's families are waiting for answers that, right now, are few and far between.
In Walker's house in Overbrook, Amaker's room has been left untouched, his bed still unmade, his sneakers scattered on the floor of a hallway closet.
Walker can barely speak about her son without crying.
"Whoever shot my son - [Green] would have never wanted it to happen to Basir," she said. "They were the best of friends."
Stevens, Bailey's brother, believes someone knows what happened to his brother. "There's always someone who saw something," he said.
For now, though, the family has tried to find what peace they can.
"The only thing we can do is remember," Stevens said.
Anyone with any information on the deaths of Basir Amaker and Karon Bailey is asked to call the police tip line at 215-686-TIPS (215-686-8477).
A $40,000 reward has been posted for information leading to an arrest in both murders. Green's murder is also unsolved. There is a $20,000 reward in that case.