Now, Shirakawa's lawyers want that charge thrown out.
Last March, Shirakawa pleaded guilty to charges of lying on campaign finance reports and gambling with public funds.
Under a plea deal, he was to spend a year in jail. However, prosecutors say new DNA evidence linking Shirakawa to an illegal campaign mailer turned up after the plea deal.
In court Friday, Shirakawa's lawyers argued prosecutors knew about the evidence and it should be included in the original plea agreement.
"What the defense has as a little hook is that one investigator had a small piece of the file in his office," Assistant District Attorney Karyn Sinunu-Towery said.
Shirakawa is expected to be sentenced this fall.