Probe of Jackson doctor to expand, legal experts say

LOS ANGELES -- The evidence police collected from Michael Jackson's personal physician's clinic and storage unit shows authorities are trying to follow a trail of drugs and looking into the doctor's record-keeping as they attempt to unravel what led to the pop star's death.

Search warrants targeting Dr. Conrad Murray's Houston clinic and storage unit mean authorities have moved into a full-fledged criminal investigation, legal experts said Friday.

Loyola University law professor Laurie Levenson said she expects to see search warrants served at more places associated with Murray and for investigators to be interviewing his employees.

Evidence already gathered includes e-mails from and correspondence addressed to Stacey Howe. Records list Howe as "administrator" at Murray's Las Vegas business, Global Cardiovascular Associates Inc. Attempts to reach her Friday were unsuccessful.

Murray, 51, was hired as Jackson's personal physician not long before he died. He was in Jackson's rented Los Angeles mansion when the singer was found unconscious June 25 and Murray tried unsuccessfully to revive him. Murray was interviewed twice by police but has not spoken publicly. Doors to his Las Vegas office were locked Friday.

Los Angeles County assistant chief coroner Ed Winter said a final determination on Jackson's cause of death is not expected until the end of next week.

Murray took a leave from his Nevada practice to accompany Jackson to London for a planned series of 50 concerts. He was to be paid a reported $150,000 per month.