Sheriff investigating Mel Gibson & Oksana Grigorieva “frustrates” prosecutors

Until the files are turned over the D.A. can’t announce whether it will charge the Lethal Weapon star with domestic violence and Grigorieva with extortion.

While the investigation was said to be “substantially done” as of last week, prosecutors now don’t believe they will receive the case until next week, at the earliest.

“The amount of hours the Sheriff’s Department has spent on investigating Oksana is mind boggling,” a source close to the case told Radar Online.

Sheriff’s officials have spent months investigating claims that someone tried to trade her silence for money from Gibson who is in a bitter custody dispute with ex-girlfriend and mother of his child, Lucia.

“It’s almost as if the cops are waiting for Oksana to commit a crime to bolster their findings, which so far, are very anemic. It’s unlikely any charges will be filed against Oksana,” the source continued.

Oksana has claimed that Mel punched her in the face on January 6 2010, while she was holding then-baby Lucia, knocking out two veneers on her upper front teeth.

Gibson admitted to slapping Oksana across the face, but denied that he ever punched her.