The L.A. County Sheriff's Department has finished its investigation into whether Gibson's ex Oksana Grigorieva or someone close to her tried to extort money from Gibson, and they have turned their findings over to prosecutors.
If charged and convicted with extortion, Grigorieva could face up to several years in prison. However, experts say the case would be difficult to prove since it's common to use incriminating evidence as a bargaining chip in civil law cases.
"You basically cannot threaten to expose family secrets in exchange for money. That is extortion. However, you can drive a hard bargain in civil settlement discussions, so this is a judgment call," said ABC News legal analyst Dana Cole.
Earlier, the sheriff's investigated allegations that the Academy Award winner hit Grigorieva at his Malibu home in January 2010. Gibson admitted in court documents only to slapping Grigorieva to restrain her from shaking their baby Lucia.
Prosecutors have not yet said whether they will file domestic violence charges.
Grigorieva waited months to report the incident. By then the couple had broken up and reached a confidential agreement regarding custody of their infant daughter.
Gibson, if charged and convicted with domestic violence, would likely not face any significant jail time since he has no prior record of the alleged crime, and it's debatable whether Grigorieva's alleged injuries rise to a felony level.
Gibson and Grigorieva are involved in a custody dispute over their 1-year-old daughter.
The Associated Press contributed to this story.