Jack Nicholson has hinted he warned tragic Heath Ledger against taking on the role of The Joker in the new Batman film. Ledger, 28 - who was declared dead at 3:30pm at his Manhattan apartment on Tuesday - publicly declared himself exhausted and sleep deprived in November following the grueling shoot for The Dark Knight. He also revealed in an interview with the New York Times he'd resorted to taking sleeping pills - an overdose of which is believed to be the cause of his death - in a desperate bid to catch up on rest. And Nicholson, who famously portrayed the menacing Joker in Tim Burton's 1989 movie Batman, implied to the waiting crowd outside plush London restaurant The Wolesley on Tuesday night he spoke to Ledger about his role in The Dark Knight - and warned him about the pitfalls of taking on such a demanding challenge. When asked by the London crowds for his reaction to Ledger's untimely demise, a defeated Nicholson simply replied, "I told him so." Batman Begins prequel The Dark Knight is due to be released in July.