District Attorney Seth Williams, who endorsed Murphy in June, dismissed as a "bull - - - - argument" Kane's recent focus on Murphy's lack of courtroom experience in Pennsylvania.
Murphy passed the bar exam in Minnesota, not Pennsylvania, but was later admitted in the commonwealth to practice law.
Kane has branded her campaign material with the slogan, "A prosecutor, not a politician."
"That's just stupid," Williams said, noting that the attorney general runs that office but doesn't try cases. "Pennsylvanians deserve better."
Murphy took his own shot at Kane for raising as an issue his support in Congress for legislation that lifted a ban on firearm sales in the District of Columbia.
"Either you believe in the Second Amendment or you don't," Murphy said. "You can't pick and choose what sections of the Constitution you believe in."
A Kane campaign spokesman was waiting outside the endorsement event to hand out a statement that made reference to Murphy's father being a former Philadelphia police officer. It also touted her work "on the front line" with law-enforcement agencies.
"I am fine with the head of FOP Lodge #5 looking after the son of a member," Kane's statement said. "I have worked with police officers for most of my career and know that they are very loyal."
Former state Auditor General Don Bailey is also running in the Democratic primary. Cumberland County District Attorney David Freed is the lone Republican in the race.
Contact Chris Brennan at 215-854-5973 or firstname.lastname@example.org, or follow on Twitter @ChrisBrennanDN. Read his blog, "PhillyClout" at www.philly.com/ philly/blogs/cityhall