Richard Senneff took to the stand to detail Murray's behaviour when he arrived at Jackson's bedside on June 25, 2009.
Senneff said that the information he received from Murray regarding the 50-year-old's underlying health issues "did not add up".
"I asked what his underlying health condition was; [Murray] did not respond," he claimed. "I think it was the third time he said, 'Nothing, he has nothing', and simply that did not add up to me."
Watch Senneff give evidence in court today below:
Senneff alleged that Murray told him he had only given Jackson the sedative lorazepam, and failed to mention that he had been giving Jackson the surgical anaesthetic propofol to help the singer sleep.
When asked why he doubted what Murray had said, Seneff explained that the presence of doctors in the house and the sight of Jackson hooked up to an IV "didn't seem normal".
Senneff added that Murray's disputed statements gave paramedics the impression that they had "a really good chance of saving" Jackson.
The singer's personal chef said on Wednesday that Murray appeared "very nervous and frantic" after discovering Jackson unconscious.
The jury has also heard a similarly distressed voicemail left by the doctor.
Listen to voicemail played to the court on Wednesday: