AN insurance payment of $10m (£5.6m) to the three-year-old daughter of Heath Ledger, the actor who died of an overdose of prescription medicines, is being withheld while his insurers try to prove that he committed suicide.

The investigation has infuriated Ledger’s family and his former fiancée Michelle Williams, the 28-year-old actress who is the mother of his daughter Matilda Rose.

Ledger, who was found dead in bed in his New York flat last January, had taken sleeping pills, pain killers and antidepressants during his final hours. But the coroner ruled that his death had been caused by an accidental overdose.

This verdict has been challenged by ReliaStar Life, the Dutch insurance company, which wants to interview the Australian actor’s Manhattan friends - including Mary-Kate Olsen, 22, the actress who may have been the last person to talk to him. Olsen’s lawyer said she had no idea where Ledger obtained his drugs.

ReliaStar said that no decision has been made on the payout. However, if it finds evidence that Ledger killed himself, it will be legally bound to return only the premiums paid on the policy rather than the full $10m claimed by his family.

Ledger took out a life insurance policy last June a few weeks before he separated from Williams, who continued to look after their daughter in New York.

Sources close to the insurance company suggest that ReliaStar suspects Ledger lied twice on his application: he did not declare that he was using prescribed drugs and that he had used illegal drugs.

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