Michael Jackson\'s doctor Conrad Murray told police he thought he was not the only medic treating the pop icon, in an interview played in court at his manslaughter trial on Friday. In the first time the 58-year-old medic\'s voice has been heard for any length in the trial, Murray told investigators how he had been working for Jackson for two months full-time when the singer died on June 25, 2009. He had treated the singer \"off and on\" since 2006 when he was approached and asked if he would be Jackson\'s personal doctor as he prepared for a series of comeback concerts in London, he said. Asked if Jackson was under the care of any other doctors, he added: \"He never disclosed that to me, but because he moved around so much I would assume that he was.\" Murray is accused of involuntary manslaughter over Jackson\'s death from an overdose of the powerful sedative propofol, with which he was treating the star for insomnia at the time of his death. The doctor\'s defense lawyers claim Jackson took extra doses of the drug while Murray was out of the room, at the star\'s mansion in the plush Holmby Hills district of Los Angeles. In the police interview played Friday -- more of which was due to be played later in the day -- Murray said Jackson personally offered him the job of caring for him during the \"This is It\" shows at London\'s O2 Arena. He only subsequently realized that he would be paid the $150,000 a month salary by concert promoters AEG. The trial has heard that Jackson was taking a significant number of drugs for insomnia and other ailments. He also regularly visited a top dermatologist, and would emerge sometimes talking slowly after those appointments.