Eszterhas sparked a war of words with the actor/director earlier this week (begs09Apr12) over claims Gibson made a series of anti-Semitic and unsavoury remarks during a vacation in Costa Rica - allegations the movie star was quick to deny - and, on Friday, (13Apr12) the Flashdance and Basic Instinct screenwriter broke his silence with an appearance on U.S. breakfast show Today - and confessed his bitter fight with the Braveheart star began after an inappropriate conversation between Gibson and his teenage son.
He said, "The most egregious episode that happened had to do with my 15-year-old son Nick, who was with us in Costa Rica as Mel's guest. And Mel shared with him a pornographic scenario, that I can only call sexual butchery, that he fantasised in terms of (ex-girlfriend) Oksana (Grigorieva).
"To put this kind of imagery into a 15 year old's head, I think is heinous. I think it's vile and I think it's unforgivable... I didn't have anything to do with Mel personally since that incident... And I never saw him, or spoke to him after that."
And the screenwriter admits he has tangible proof of Gibson's violent, inappropriate behaviour.
He continued, "I have a tape that my 15-year-old son made in the middle of a violent charade in Costa Rica... where he said the vilest and most threatening things. Nick got his iPod (to tape it) because he was frightened about what was going to happen.
"There were also witnesses. My wife was there, the house manager was there. The situation in Costa Rica was so bad, that the help said, 'If there are kids, get out of the house and hide,' - because he was so out of control. My son Nick wound (sic) up snatching a butcher knife from the kitchen and sleeping with it under his pillow because he was so frightened."
But Eszterhas isn't sure if he's going to release the video footage, adding, "I don't know what I'm going to do with the videotape... I don't like to be called a liar... that's why I'm here."
The feud between Gibson and the screenwriter began when Eszterhas learned his script for a planned film about Judah Maccabee, a Jew who led a revolt against the Seleucid Empire, had been rejected by bosses at Warner Bros. Gibson is to direct the epic drama.
Eszterhas accused Gibson of announcing The Maccabees project in "an attempt to deflect continuing charges of anti-Semitism which have dogged you, charges which have crippled your career."
Gibson responded with an open letter to the screenwriter, which read, "Contrary to your assertion that I was only developing Maccabees to burnish my tarnished reputation, I have been working on this project for over 10 years and it was publicly announced eight years ago. I absolutely want to make this movie; it’s just that neither Warner Brothers nor I want to make this movie based on your script."