As the pace of new Mel Gibson rant tapes has slowed down, news emerged on Wednesday that the investigation into allegations of domestic abuse by the troubled actor's ex-girlfriend, Oksana Grigorieva, has been expanded to include a probe into whether the aspiring singer attempted to extort money from the "Lethal Weapon" star.

According to the target="_blank">Los Angeles Times , a Los Angeles County sheriff's spokesperson said that investigators are "looking into" claims of an extortion attempt related to the series of taped arguments between Gibson, 54, and Grigorieva, 40, that have been leaked on RadarOnline over the past few weeks.

Sheriff's detectives are in the midst of an investigation into whether Gibson struck Grigorieva while she was holding the couple's infant daughter during an argument in January. Unnamed sources close to the investigation said detectives met with Gibson's lawyers — who have denied the allegations of physical abuse — in the domestic violence inquiry on Tuesday. The detectives also recently obtained copies of the explosive audio tapes during a closed-door hearing in the couple's child custody case.

Though Gibson's camp has not made any statement on the tapes, his representatives have not denied that the voice heard hurling racist and sexist slurs and threatening violence on the recordings is that of the Oscar-winning star. The Times noted that it's questionable whether the tapes — including one section in which Gibson tells Grigorieva that she "deserved" to be hit — would even be admissible if a domestic violence case went to criminal court because it appears that they were recorded without Gibson's knowledge. California law requires that both parties must consent to having a conversation recorded; the paper said that under normal circumstances, not having the consent of one of the participants would make the tapes inadmissible in court and possibly open the taper to criminal charges. The tapes would not be considered illegal if the person recording them did so because he or she thought the conversations related to the commission of a felony involving violence.