He also failed a drug screening, a condition of his parole.
Had the terms of probation been enforced, Officer Walker might still be alive.
Only 23, Jones was far more familiar with the criminal justice system than city schools or holding a legitimate job, ricocheting in and out of courts and jails since age 15.
His grandmother told the probation officer she didn't want him living in her house.
"This is a house of peace," she said. "I didn't need the drama."
Jones served every day of his four-year sentence for gun possession, suggesting that he met no standards for early release.
His prison term seems to have taught him little.
Since Jones' release last October, he has been arrested for armed robbery and possession of an illegal gun. The case collapsed, as so many routinely do, after the victim failed multiple times to appear to testify. Jones tested positive for drugs. He told a state parole officer that he had smoked marijuana while he was locked up this summer.
Did I mention that Jones was shot during his brief period of freedom?
At the probation-violation hearing in July, Judge Susan I. Schulman gave Jones a tongue-lashing that is poignant in retrospect.
"There will be no positives, Mr. Jones," she said. "One positive, Agent [Jose] Rodriguez, you drop the detainer," meaning one failed drug test, and Jones would be locked up. "With your record, you cannot afford to think that you still make the rules. You do not. I do. Agent Rodriguez does."
But Jones continued to make his own rules, continuously violating the terms of parole.
He failed to find work, enroll in GED classes, or perform community service. In this regard, he isn't much different from the thousands of young ex-cons clogging the courts and draining the system. The difference is that Jones is charged with killing a cop.
Judges see hundreds of criminal cases, and Schulman is a strong, conscientious judge who, at the probation hearing, ordered him placed on house arrest. Trouble is, the ruling was so loosely enforced that it failed to keep the streets safe for a police officer.
At that hearing, the assistant district attorney told the judge: "Your Honor, Mr. Jones is not taking probation seriously."
Unfortunately, supervisors at the state Board of Probation and Parole didn't appear to take Jones' probation seriously enough, either.
Within days of the judge's lecture, Jones failed another drug test.
He should have been locked up then.
Three days before Walker's murder, The Inquirer's Allison Steele and Mike Newall have reported, Rodriguez requested a warrant to detain Jones. Supervisors, according to sources, denied the request.
In his official statement, state probation and parole board chair Michael C. Potteiger offered his sympathies to Walker's family, saying, "We are all deeply saddened by this senseless tragedy."
In a detailed summary of events, Potteiger made no mention of Jones' testing positive or the request for a warrant.
As for the failure to hook up electronic monitoring, he said that Jones was a "special probation" case who had been given two weeks to install a landline in his house so the device could be imposed.
Given Jones' consistent and flagrant flouting of the imposed rules - to be fair, he appears to have routinely checked in with Rodriguez - this approach proved tragically misguided and technologically obsolete.
The board better adjust quickly to the reality that many ex-offenders, with limited funds, no longer have landlines in a world of cellphones.
Last week, Gov. Corbett called for an investigation "to determine if there were any policy failures of employees or employee errors."
Four years ago, after Officer Patrick McDonald was murdered by an ex-offender recently released from prison, then-Gov. Ed Rendell ordered a comprehensive review of the system. The board embraced the report and determined it had reformed itself.
In a system so strained and stressed, with thousands of ex-offenders to manage, mistakes will happen. Now another governor has ordered an investigation. Recommendations will be made. Staff may be reprimanded.
Officer Walker will still be dead.
In July, Judge Schulman told Jones: "Unless you enjoy spending your years behind bars, it's time to get it together."
Which, of course, he didn't. Nor did the system.
Contact Karen Heller
at 215-854-2586 or firstname.lastname@example.org, or follow on Twitter at @kheller.