The District Attorney’s Office could soon be joining the Fair Political Practices Commission (FPPC) in investigating County Supervisor George Shirakawa for his failure to file campaign disclosure forms the last four years. This week the DA requested all correspondence between Shirakawa’s office and the county Registrar of Voters,  the Mercury News reports. The Merc has been following up on the story Metro broke last month, which found that Shirakawa chose not to file forms the last four years disclosing how he has raised money to pay off a $110,000 debt he incurred during his 2008 supervisor campaign.