Updated

Christian Bale says that his late co-star Heath Ledger was "intense" in his portrayal of the Joker in the forthcoming Batman movie "The Dark Knight," but was otherwise pretty calm during filming.

"He was incredibly intense in his performance but incredibly mellow and laid-back," Bale, 34, tells Details magazine in an interview in its June/July issue, according to Us Weekly.

Ledger, 28, was found dead Jan. 22 in his Soho loft apartment in New York City of an accidental overdose of prescription pills.

Shortly before his death, he had spoken about how playing the Joker had tormented him, and he couldn't sleep during the filming of "Dark Knight."

Bale said Ledger's performance was grittier and more maniacal than those of actors who have played the character in the past.

"Certainly there was a great anarchist streak to it — just getting dirtier than anybody's envisioned the Joker before," he told Details. Ledger's Joker had "power because he has no limits — absolutely nothing to lose."

The Details issue hits newsstands June 3. "Dark Knight" opens July 18.

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