But for five years, police and prosecutors continued to pursue the killing of a young person who came here to help. Now, authorities said Thursday, they finally have enough evidence to file charges against the suspect they have long believed killed Zabel - a man already serving a life sentence for shooting to death his suspected accomplice in the slaying.
"An arrest is imminent," Capt. James Clark, commander of the Police Homicide Unit, said Thursday night as multiple sources told The Inquirer that a warrant was being prepared for Marcellus Anthony Jones, 35, of North Philadelphia.
Clark said he could not comment further on the case until charges were formally filed, a development that could happen as early as Friday morning, the sources said.
This year, The Inquirer published a five-part series on the fifth anniversary of Zabel's death.
In recent weeks, the sources said, at least three of Jones' family members and friends have been interviewed by detectives from the Homicide Special Investigation Unit, which specializes in cold cases.
The break came last month, when detectives received a letter from an acquaintance of Jones' who said he had knowledge of the case.
The letter led investigators to interview Jones' family, and at least one told police that Jones had spoken directly about the Zabel killing, the sources said. Investigators also had the family members review grainy surveillance footage of Zabel's killer fleeing the scene.
Jones - a three-time convicted violent felon who was on parole at the time of Zabel's death - has long been the prime suspect.
Prosecutors won a life sentence against Jones last year in the shooting death of Tyrek Taylor. They argued that Jones shot Taylor, 20, once in the back of the neck as he got out of his car one morning in front of his mother's South Philadelphia house, three months after Zabel was killed.
Taylor was the getaway driver in Zabel's death, they said, and Jones killed him to keep him quiet.
A month after Zabel's slaying, police connected Taylor and Jones to the killing through a cellphone stolen in another South Philadelphia robbery.
At the 2012 trial, prosecutors were able to link the killings of Taylor and Zabel through the testimony of Devonne Brinson, who said Jones had spoken to him about the slayings in jail.
"He told me he had to do it," Brinson testified about Taylor's death. "Because [Taylor] might be snitching on him for what they did to the teacher."
While prosecutors were able to argue that Zabel's death was Jones' motive for killing Taylor, they did not have enough evidence to arrest Jones in Zabel's slaying. And while Brinson's testimony was crucial, they said they needed at least one more witness.
At the time, investigators said they hoped that with Jones off the street, other witnesses would step forward and provide them with the "final link" they needed.
They said they wanted to be able to call Zabel's parents and say that they not only knew who killed their son - but they were charging him with the crime.
In Zabel's hometown of Austin, his mother, Lana Hollerud, said Thursday night that she had spoken with investigators and was "overwhelmed" to learn that there could be justice for her son.
She had attended Jones' trial for killing Taylor - and left convinced that he was the man who killed her son. But she returned to Minnesota never thinking investigators would get the evidence they needed, that too much time had passed.
She said she was surprised by how happy she was.
"I believe people should be held accountable for their actions, and that was the part that was always missing," she said. "Someone hurt Beau and they weren't being held accountable for it."