A detective testified on Monday that Michael Jackson's doctor said he noticed the singer stopped breathing earlier than prosecutors contend, raising a question of how closely the physician monitored Jackson after giving him the key drug that caused his death.

Prosecutors claim Dr. Conrad Murray was negligent in his care for the "Thriller" singer and on the day he died, Murray spent time covering up evidence of mistreatment instead of seeking help from paramedics after he discovered Jackson had stopped breathing.

Previously, prosecutors said that judging by phone records, as much as 20 minutes may have passed, but Monday a detective who questioned Murray two days after Jackson's death on June 25, 2009, offered times suggesting more than an hour elapsed.

Police detective Orlando Martinez testified that Murray admitted giving Jackson propofol -- the key drug responsible for his death -- between 10:40 a.m. and 10:50 a.m.

Murray told Martinez Jackson fell asleep around 11 a.m. and that after monitoring him for a time, the doctor went to the bathroom and came back to see he was no longer breathing.

"According to Dr. Murray, is this sometime shortly after 11 a.m. in the morning?," Deputy District Attorney David Walgren asked Martinez.

"Yes," the detective said.

Phone company officials and another detective testified last week that Murray was on a series of calls for business and personal reasons from 11:07 a.m. until noon. Prosecutors say phone records show paramedics were not called until 12:21 p.m.

Murray has admitted giving the anesthetic propofol to Jackson as a sleep aid at the singer's mansion, even though the drug is normally used in hospital settings. But he has pleaded not guilty to the charge of involuntary manslaughter.

Following the preliminary hearing, which could end as soon as this week, a judge will determine if enough evidence exists for Murray to stand trial for involuntary manslaughter.

In other testimony Monday, pharmacist Tim Lopez said that through his business Applied Pharmacy Services, he sold Murray more than 250 vials of propofol between April and June 2009.

He also said he sold Murray exactly 20 vials of the sedative lorazepam which was also in Jackson's system and contributed to his death, according to coroners.