According to TMZ, Grigorieva's lawyers intended to use tapes allegedly of Gibson cursing and threatening her as evidence that the actor is a danger to their 8-month-old daughter, Lucia.
The 40-year-old Russian musician recorded several explosive phone calls with Gibson.
RadarOnline, a celebrity website, has been releasing pieces of the controversial conversations. The profanity laced calls have included several racial slurs and threats of violence.
In the latest excerpt released by the celebrity website, Gibson is so angry he sounds breathless.
"I will never forgive you," Gibson screams. "I will never forgive you for what you have done to me!"
Gibson's attorneys do not dispute that it is the voice of the Oscar-winning actor/director.
Another expletive-filled phone call refers to a sexual episode that never happened because someone fell asleep.
"I deserve to be ... (expletive deleted) first, before the ... (expletive deleted) jacuzzi," Gibson is heard saying in the recording, posted on celebrity website RadarOnline.com (Warning: It contains strong language). "Ok, I'll burn the goddamn house up, but ... (expletive deleted) me first! How dare you! How ... (expletive deleted) dare you," he screams.
In addition to the couple's bitter custody dispute, the raging recordings are also part of a domestic violence investigation against Gibson. Grigorieva claims that the actor hit her Jan. 6 and broke several of her teeth.
"What kind of a man is that?" she is heard saying in the recording, posted on celebrity website RadarOnline.com (Warning: It contains strong language). "Hitting a woman when she's holding a child in her hands? Breaking her teeth twice in the face! What kind of man is that?"
While many people are wondering what impact the tapes will have on Gibson's career, others are questioning just how authentic the recordings are.
"In the tapes themselves, there are several things that would raise a red flag as an expert," said Arlo West, an audio forensic expert. "I found gaps, transients and fades. All three of these things would be considered in authenticating the audio itself."
Gibson's attorneys were expected to argue that the tapes have been altered and should not be admitted into evidence. It will be up to the judge to determine if the recordings are authentic.
The case is sealed and all proceedings have been done in closed session.
Meanwhile, detectives investigating Gibson for a possible domestic violence case have received the audio recordings from the court.
Sheriff's spokesman Steve Whitmore said CDs were turned over during the court hearing. The hearing was attended by several sheriff's investigators, including detectives who look in possible child abuse.
Gibson will likely have to be interviewed by the Department of Children and Family Services which is a standard procedure when there are allegations of endangerment.
Detectives are looking into allegations that Gibson harmed Grigorieva during the January confrontation. He said he would not speculate on when the case would be turned over to prosecutors, who will decide whether Gibson should face criminal charges.
The Associated Press contributed to this story.