Prosecutors added a new perjury count and other criminal charges Thursday against Pennsylvania's attorney general, saying they found a signed document that contracts her claims she never agreed to maintain secrecy of a grand jury investigation in 2009, before she took office. 

The Montgomery County district attorney charged Kathleen Kane with felony perjury and two misdemeanors -- false swearing and obstruction -- based on a signed secrecy oath she signed shortly after taking office in early 2013. 

Kane, the first woman and first Democrat elected as attorney general in Pennsylvania, was previously charged with perjury, conspiracy and other offenses. Prosecutors said she leaked secret grand jury information about a 2009 investigation to a newspaper and then lied about it. 

An affidavit filed by a county detective said Kane has repeatedly said, directly and through her lawyers, that she did not swear to keep secret the 2009 grand jury information about a former head of the NAACP in Philadelphia. 

But the district attorney's office said her signed oath was recovered during a search of her Harrisburg offices on Sept. 17, contradicting her claims that no such document existed. 

"Kane perpetuated this falsehood not just before (a) grand jury, but also in legal filings before the Pennsylvania Supreme Court and to the people of Pennsylvania through privately retained representatives," wrote Montgomery County Detective Paul Michael Bradbury, who attached a photocopy of the one-paragraph oath to the affidavit. 

Kane's criminal defense attorney, Gerald Shargel, did not immediately return a phone call seeking comment Thursday morning. A spokesman for Kane's office referred questions about the latest charges to her personal attorneys. 

Authorities say Kane and other top aides were compelled to sign the secrecy oath and three others just like it that applied to other grand jury panels to participate in a transition meeting on Jan. 17, 2013, that concerned the office's investigations. 

Bradbury said agents learned about the existence of the signed secrecy oaths only after arresting her Aug. 6 over leaks to the Philadelphia Daily News last year. 

A district judge determined in late August that there was sufficient evidence to send those charges to county court for trial. Kane has consistently denied the allegations and has argued that she was a stay-at-home mother when the grand jury was meeting in 2009 so its secrecy provisions could not apply to her. 

The Pennsylvania Supreme Court last week issued a temporary suspension of Kane's law license, a suspension that will take effect later this month.