The King Of Pop's increased drug dependency was said to have begun taking its toll on the singer's mental and physical health days before he died on Thursday.
Jackson, who was almost bankrupt at the time of his death, was claimed to have suffered further exhaustion stemming from rehearsals for his 50 show concerts, which were due to begin at O2 arena on July 13.
'Michael was convinced that if he didn't perform in London he would die. He would say, 'They will kill me', but no one ever really understood who he was talking about. He seemed paranoid,' The Sun quoted a source as saying.
Another source close to him added: 'There were serious concerns for his mental health near the end -- so much so that he was seeing a psychiatrist.'
'He said he was being pushed into a corner and had an irrational fear that he would die or be killed if he did not perform in London. He kept saying that he had to do the concerts because he owed too much money.
'But all the time he was saying these things, his body was starting to shut down as he became more and more dependent on drugs.
'His friends say he signed his death warrant when he put pen to paper for the O2 shows. He wasn't up to it physically or mentally.'
Jackson, 50, was speculated to have suffered a cardiac arrest due to a fatal dose of prescription drugs but medics are yet to determine the cause of his death.