Michael Jackson's personal physician, Dr. Conrad Murray, administered a powerful drug that authorities believe killed the singer, a source close to the Jackson family and with knowledge of the investigation confirmed to CNN on Monday.
Murray allegedly gave Jackson the anesthetic propofol in the 24 hours before he died, the source said.
The doctor's attorneys had no comment on the report but in the past have said Murray never prescribed or administered anything that could have killed the pop star.
Murray was the doctor who was at Jackson's home when the pop star died on June 25.
Last week, Texas authorities searched Murray's Houston medical office and storage unit, looking for "evidence of the offense of manslaughter," according to court documents.
Ed Chernoff, a Houston lawyer hired by Murray soon after Jackson's death, confirmed at the time that Los Angeles Police detectives and federal Drug Enforcement Administration agents used a search warrant to enter Murray's office in northeast Houston Wednesday morning.
Chernoff said members of Murray's legal team were at the medical office during the search, which he said "was conducted by members of the DEA, two robbery-homicide detectives from the Los Angeles Police Department and Houston Police officers."
Tammy Kidd, a spokeswoman at Chernoff's office, told CNN the search "was absolutely a surprise to us, because we've had open lines of communication this whole time."
Meanwhile, the Los Angeles County coroner's office continues to investigate the cause of Jackson's death on June 25. It has been waiting on toxicology lab results, but a final autopsy report is expected as soon as this week, a coroner's spokesman has said.