The Santa Clara County District Attorney's Office is examining "irregular" signatures on campaign expense filings by former Supervisor George Shirakawa going back to 1995, an official has confirmed.

The reports date to when Shirakawa filed expense documents with the San Jose City Clark's office prior to campaigns he ran for San Jose City Council, Assistant District Attorney Karyn Sinunu-Towery said.

"We're taking a look at some irregular signatures on campaign reports from 1995," Sinunu-Towery said.

Shirakawa resigned from the Board of Supervisors on March 1 after agreeing to plead guilty to four counts of perjury, one count of felony misuse of public funds and seven misdemeanors related to illegal campaign and public expenditures.

He was appointed to the San Jose City Council in 1994, campaigned for and won a four-year term on the council in 1998 then served as a trustee on the East Side Union High School District from 2002 to 2008.

Shirakawa, a U.S. Army veteran and the son of the late San Jose City Councilman George Shirakawa Sr. who died in 1994, was elected as District 2 supervisor in 2008 and reelected last November.

San Jose acting City Clerk Toni Taber said that on Monday she turned over to the district attorney's office copies of Shirakawa's San Jose city campaign reports from 1995 to 2004 after finding a suspicious signature on one from 2001.

The signature of Shirakawa campaign treasurer Gary Clark on a 1998 campaign spending report Form 460 -- attesting to the accuracy of its accounting -- was "light and fluid," Taber said.

But on the 2001 report, she noticed that the handwriting of the signature on the official document had changed "from fluid to really choppy," Taber said.

"You could really see the pen hesitate," Taber said. "There were dots on the line instead of being a fluid motion."

After looking at the inconsistent signature, "My first thought was I have to meet with the DA," Taber said.

Taber also noted that the 2001 report listed "June cleanup" and "Petty Cash" as reasons for expenses without explaining how the money was actually spent.

Her office next will examine a box containing Shirakawa's statements of economic interest, Form 700, while he served on the City Council, Taber said.

Records of his spending using city credit cards while on the council, including bank statements, were destroyed years ago, she said.