There has been no confirmation the voice on the tape is that of Gibson, but so far, no one has denied it is him.
During his rant, heard in the third audiotape released, the actor accuses Grigorieva of using him for his money and says he owns her, in addition to berating the former couple's nanny and referring to her with a racial epithet.
The entire recording was submitted to a judge in family court. Gibson and Grigorieva are at odds about money and custody of their 8-month-old daughter, Lucia.
He argues that even though he lives in a house separate from the Russian musician he pays all the bills.
The website reports that she rejected a $20 million settlement. In the recording, there are hints of financial problems and that he has to rein in his expenses.
"I'm paying my tax money instead of the credit card bill," said Gibson. "Don't you get it?"
In earlier excerpts, the 56-year-old actor unleashes racial slurs against blacks, and profane remarks about women. Yet it is more than words that has him in trouble. She states he struck her.
"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?"
"Oh, you're all angry now!" Gibson responds. "You know what, you ... (expletive deleted) deserved it!"
Gibson goes even further by threatening to kill her.
"I'll put you in a ... (expletive deleted) rose garden," he said. "You understand that? 'Cause I'm capable of it."
Both sides have reportedly gotten restraining orders against the other.
"Mel Gibson would have a difficult time if he were prosecuted because those tapes are very damaging to him," said attorney Gloria Allred.
Shortly after the release of the first tape, the William Morris agency dropped Gibson as a client. According to Variety, sources at the agency made the decision earlier in the week, after Gibson's longtime agent died.
Gibson's publicist says the split was a mutual agreement.
The actor has not publicly discussed the breakup with the 40-year-old singer. The former couple first revealed their relationship shortly after Gibson's wife, Robyn, filed for divorce last April. The divorce is pending.
In 2006, the Academy Award-winner came under fire for a racially charged tirade when he admitted to making anti-Semitic remarks during a drunken driving arrest. He issued an apology at the time, and appealed to the Jewish community to help him recover from his alcohol addiction.
The Associated Press contributed to this report.