EXCLUSIVE: Oksana's Lawyers Compiling Mel Gibson 'Dirt File' To Prove He's 'Crazy' & Strip Him Of Child Custody

"There has never been any doubt about the authenticity of the tapes, however Oksana's lawyers believe that if an independent and world renowned expert verifies it is indeed Gibson on the tape, which it is, the judge in their child custody case will be compelled to take action and strip him of his rights," a source with knowledge of the situation told RadarOnline.com.

Despite Grigorieva's protests to date that the Lethal Weapon star is unfit to care for his child, Los Angeles Superior Court Judge Scott M. Gordon has upheld an agreement she signed, in May, last year.

That deal, which Grigorieva later turned her back on, ensured the pair would share 50-50 custody of Lucia and granted Gibson overnight visits.

Said one source: "The dossier will be presented to the court by way of explanation that Gibson clearly should not be granted the custody he currently enjoys with Lucia.

"It will be argued that the court is not acting in the best interests of Lucia."

The "dirt file" will also include other times Gibson has allegedly flown of the handle, RadarOnline.com has been told.

Grigorieva alleged she was subjected to verbal and physical abuse at the hands of the star, culminating in a nuclear blow up on January 6, last year, when he punched her in the head, knocking out two veneers on her upper front teeth.

In a sworn declaration in the couple's family law case, Gibson confessed to slapping Grigorieva during an argument, but denied hitting her.

Gibson countered Grigorieva with the charge that she tried to extort millions of dollars from him in return for keeping the telephone recordings secret.