WASHINGTON • American actor Johnny Depp was grilled about his drug and alcohol use as he took the witness stand on Thursday for a third day at his defamation case against his ex-wife, actress Amber Heard.

Heard's lawyer Ben Rottenborn spent more than five hours seeking to undermine the credibility of the Pirates Of The Caribbean (2003 to 2018) star before the seven-person jury hearing the suit in Fairfax County Circuit Court.

Depp, 58, was asked about his thrashing of hotel rooms and the circumstances of an incident in Australia, in which the tip of the middle finger on his right hand was severed.

Depp testified on Wednesday that it was caused by a furious Heard throwing a vodka bottle at him.

Her lawyer told the jury that Depp had told doctors he cut himself with a knife.

Depp acknowledged during cross-examination that after his finger was cut, he used the wounded digit to scrawl messages around the house using his own blood and paint.

Heard's lawyers played a video at one point of Depp slamming cabinet doors in their kitchen and pouring himself a large glass of red wine.

"I did assault a couple of cabinets, but I did not touch Ms Heard," Depp said when asked about the video.

In an audiotape played by her lawyer of a conversation between Depp and Heard, she complains about having bruises on her head, a split lip and a black eye.

Heard's lawyers have claimed Depp would become a "monster" during drug-and alcohol-fuelled benders and physically and sexually abuse Heard.

Depp has denied the allegations and claimed it was Heard who was frequently violent during their relationship.

He filed a defamation suit against Heard over a column she wrote for The Washington Post in December 2018, in which she described herself as a "public figure representing domestic abuse".

Heard, who starred in the movie Aquaman (2018), never named Depp - but he sued her for implying he was a domestic abuser and is seeking US$50 million (S$68 million) in damages.

The Texas-born Heard, who turned 36 yesterday, counter-sued, asking for US$100 million and claiming she suffered "rampant physical violence and abuse" at his hands.

Depp and Heard met in 2009 on the set of the film, The Rum Diary, and were married in February 2015. Their divorce was finalised two years later.

Mr Rottenborn probed Depp extensively about his drug and alcohol use, including partaking with shock rocker Marilyn Manson.

"We drank together. We've had cocaine together, maybe a couple of times," Depp said. "I once gave Marilyn Manson a pill so that he would stop talking so much."

Depp acknowledged using drugs and alcohol to "numb the residual pain from my youth", but denied Mr Rottenborn's suggestion it was to excess or that he would ever "black out".

Mr Rottenborn read text messages from Depp to various people in which he apologised for his behaviour and sought the advice of English singer Elton John on how to get clean.

"Once again, I find myself in a place of shame and regret," he said in a May 25, 2014, text to Heard. "I will never do it again. I want to get better for you."

Depp admitted that he has taken out his anger on objects in the past, but denied ever striking Heard.

"I don't believe I'm the only human being who has ever punched a door," he said. "I have assaulted a couch or two."

Depp filed the defamation complaint in the United States after losing a separate libel case in London in November 2020 that he brought against The Sun for calling him a "wife-beater".

AGENCE FRANCE-PRESSE