At a news conference late Wednesday afternoon, police officials said the man they were questioning is believed to be one of two suspects who appeared in surveillance videos tailing Walker early Saturday morning.
"We believe he is going to be our shooter," Homicide Capt. James Clark said.
No one has been charged yet in connection to Walker's murder.
Police said they are still searching for the second person in the videos and are asking for the public's help.
"Oh, we'll get him," Police Commissioner Charles Ramsey said, adding that police still have "a lot of work to do" but have "a good solid lead."
Over and over, Jones, who has a history of gun, theft, robbery and assault charges, violated probation, but somehow he was able to walk free.
Common Pleas Judge Susan Schulman gave Jones strict restrictions on July 25 for violating parole. He was placed on state house arrest, must complete community service, seek and maintain employment, complete a GED program and submit to weekly drug screens.
On Aug. 10, Jones turned in a urine sample that was positive for drugs, according to a source. Jones' probation officer told Jones to come in to the office last Wednesday, Aug. 15, for his weekly report. The probation officer also apparently asked a supervisor to approve obtaining a warrant for Jones' arrest for violation of probation.
No bench warrant was issued.
Three days later, Walker was gunned down, just blocks from his precinct, after he finished his shift.
On Jan. 24, 2008, Jones faced numerous gun charges and other charges including possession of marijuana, recklessly endangering another person and resisting arrest.
On April 1, 2008, he was sentenced to two to four years in prison, then 3 years probation after being found guilty of the gun charges.
While on probation, on Feb. 13, 2012, Jones was arrested in another case - robbery, possession of a firearm prohibited, theft, receiving stolen property, simple assault and recklessly endangering another person. On April, 19, the prosecutor was not ready and the witness failed to appear. On June 12, the case was withdrawn.
All along, Jones was violating probation on the 2008 case. On March 26, 2012, a hearing was continued for violation of probation in connection with that case. Four months later, Judge Schulman put him on electronic monitoring.
When Jones was 18, on October 16, 2007, he was arrested on numerous charges including gun charges, aggravated assault, terroristic threats with intent to terrorize another, simple assault and recklessly endangering another person. All charges were withdrawn.
Contact Julie Shaw at firstname.lastname@example.org or 215-854-2592. Follow her on Twitter @julieshawphilly.