Mel Gibson will be interviewed again by police officials in connection with the ongoing extortion investigation regading his ex-girlfriend, Oksana Grigorieva.

The second round of questions shows how seriously police are taking the investigation of Oksana and Mel's claim that she tried extorting him for millions.

At the center of the claim? The Mel Gibson tapes.

Will Mel and/or Oksana face criminal charges?

The actor, who contends Oksana Grigorieva recorded and used the tapes in an attempt to secure a financial settlement, has cooperated with police so far.

He'll continue to cooperate by sitting for another interview, at which officials say they won't ask questions about the concurrent domestic violence case.

Sheriff's officials just turned the domestic violence case over to the D.A., but no charges have been filed ... yet.  The extortion investigation continues.