Johnny Depp grabbed his then-wife Amber Heard by the hair and repeatedly struck her in the face during a heated argument about a month after their marriage, her sister said Wednesday.

Heard also punched Depp during the March 2015 fight at their Los Angeles penthouse, Whitney Henriquez testified at the high-profile defamation case between the celebrity couple.

Henriquez, Heard's 34-year-old younger sister, said the "Pirates of the Caribbean" star sought to have her sign a non-disclosure agreement after the incident, but she declined to do so.

The 58-year-old Depp filed suit against Heard over an op-ed she wrote for The Washington Post in December 2018 in which she described herself as a "public figure representing domestic abuse."

Heard, who had a starring role in "Aquaman," did not name Depp in the op-ed, but he sued her for implying he was a domestic abuser and is seeking $50 million in damages.

The Texas-born Heard countersued, asking for $100 million and claiming she suffered "rampant physical violence and abuse" at his hands.

Depp, during his four days on the witness stand, denied ever striking Heard and claimed that she was the one who was frequently violent.

Henriquez testified on behalf of her sister on Wednesday -- day 18 of the trial being heard by a seven-person jury in Virginia.

Henriquez, who lived for a time in the same penthouse complex as Depp and Heard, said the couple had a volatile relationship.

"When he was sober things were wonderful," she said. "When he wasn't sober they were terrible."

"If he was using or if he was drinking there was almost always a fight," she said.

- 'Saying really nasty things' -
Henriquez recounted in detail the March 2015 incident at the Los Angeles penthouse complex owned by Depp.

She said Heard woke her up in the middle of the night to tell her that Depp had been cheating on her and that the newly married couple then got into a fight.

"They were saying really nasty things to one another," Henriquez said.

"Johnny runs up the stairs," she said. "He comes up behind me, strikes me in the back kind of."

"I hear Amber shout 'Don't hit my fucking sister,'" she said. "She smacks him, lands one."

Henriquez said Depp's bodyguard moved to intervene, "but by that time Johnny had already grabbed Amber by the hair with one hand and was whacking her repeatedly in the face with the other."

The bodyguard pulled them apart, she said, and Depp then proceeded to trash the penthouse, breaking numerous items in the kitchen and emptying racks of Heard's clothes on the ground.

Depp's lawyers have put experts on the stand who testified that he has lost millions because of the abuse accusations, including a $22.5-million payday for a sixth installment of "Pirates."

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."

Depp, a three-time Oscar nominee, and Heard met in 2009 on the set of "The Rum Diary" and were married in February 2015. Their divorce was finalized two years later.

Judge Penney Azcarate has scheduled closing arguments in the case for May 27, after which it will go to the jury.