LOS ANGELES—The investigation of Michael Jackson’s death is widening as questions intensify about the drugs he took, the doctors who provided them and the actions of police.

Why didn’t police seal the mansion where he had been living? Why didn’t they get immediate search warrants? Why did they tow away a doctor’s car right after the death but not declare the home a crime scene? And why was Jackson’s sister Janet allowed to move possessions out of the mansion two days after the death, before police searched it?

Los Angeles police say proper procedures were followed based on the circumstances officers encountered when they were called to the home at 12:21 p.m. on June 18. A doctor was attending to Jackson and stayed with him when he was placed in an ambulance at 1:07 p.m. There was no sign of foul play. Others say police should have assumed it was possible a crime occurred and taken precautions to ensure the scene was not disrupted so evidence wasn’t lost or tainted.

“If I was the chief detective on the case, I would have said, ’We don’t know what’s going on. We should seal the scene,”’ said defense attorney Harland Braun, who has represented celebrities including Robert Blake, Roseanne and Gary Busey. “You always have to think of the worst-case scenario and you have to think fast. I would have sealed the scene just because it was Michael Jackson.”