One of Michael Jackson’s former physicians claims he tried to warn the pop star about the dangers of using the powerful anesthetic propofol, according to People. A lawyer for Dr. Allan Metzger –an L.A.-based rheumatologist who was Jackson’s doctor prior to 2003– claims his client told Jackson about the dangers of using the sedative during a visit to the singer’s home in April. Investigators believe Jackson was given propofol the night before his death by his personal physician, Dr. Conrad Murray, one of four doctors whose offices have been searched in the ongoing probe into the singer’s death.