TMZ has learned Oksana Grigorieva just went to the law offices of an attorney -- a former federal prosecutor who specializes in computer crimes -- considered one of the foremost authorities on Internet crimes.
The attorney -- James Spertus -- practices in West Los Angeles. Oksana is in his office right now.
It's interesting ... because sources tell TMZ Mel Gibson's lawyers have told the Sheriff's Department that they have evidence someone tampered with the tapes and they want Oksana investigated.
Spertus has lectured FBI agents and prosecutors on prosecuting intellectual property crimes. He is the founding member of the Computer Crimes and Intellectual Property Section of the United States Department of Justice.
We spoke with Spertus, who would not comment about Oksana.
UPDATE: Sources connected with Oksana tell us she has been advised to make a copy of her hard drive in the event the Sheriff's Department seizes her laptop in connection with the criminal investigation.