TMZ has learned ... Mel Gibson's lawyer is meeting with Sheriff's investigators right now, presenting evidence she believes proves Oksana Grigorieva has fabricated the case against her client.
The meeting is being held at a courthouse in Los Angeles, in a conference room.
In addition to presenting evidence that Mel did not strike Oksana, we're told attorney Blair Berk will ask Sheriff's deputies to go after Oksana for extortion and falsifying evidence.
Berk's track record may be just what Mel needs. Last year she convinced New York prosecutors not to file felony assault charges against her client, Kiefer Sutherland, after he broke a dude's nose at a party. Berk also convinced an L.A. judge last fall to dismiss battery charges against Kanye West, who was caught on video breaking a camera.
After the meeting, we got video of Blair Berk and L.A. County Sheriff's Detective Tom Lewis. We asked Berk if Oksana was guilty of extortion and lying to the cops. She said it was an "inappropriate question." Lewis was mum.