"There's a lot that goes into being able to prove whether someone was murdered or not, and that takes a long investigation," LAPD Commander Patrick Gannon tells PEOPLE. "The death of Michael Jackson is considered undetermined at this point as to whether it was a homicide or accidental or some other cause of death."
Still, Gannon's team is consulting with the same state and federal drug enforcers who, after a two-year probe, brought a criminal case against Anna Nicole Smith's lawyer, Howard K. Stern, and two of her doctors.
"There are agencies that played a role in that particular investigation that we have sought out for their expertise," Gannon says. "We've reached out to the state attorney general and the DEA and others."
Multi-Agency StudyIn addition to the DEA, detectives have teamed up with the county coroner and prosecutors in the L.A. District Attorney's office for what police have internally labeled a homicide investigation, insiders say.
Regardless of how the case is labeled, investigators have their work cut out for them in trying to determine which, if any, specific doctors should be held accountable for the death of a man who for years saw a lot of doctors and took numerous medications.
"L.A. doesn't want another celebrity trial that they'll lose," says former L.A. County prosecutor Robin Sax Katzenstein, who sees this as a possible involuntary manslaughter case. "There's so many issues that make this a difficult case."
Call for ArrestsEven if police find that a doctor gave Jackson a potentially fatal drug, they would also have to prove the doctor knew he was giving Jackson something he shouldn't have. That could be a problem if Jackson had taken the same medications before without incident.
Loyola Law School Professor Laurie Levenson agrees with Katzenstein's prediction that this is an involuntary manslaughter case, at best. She adds that, although some heartbroken Jackson family members have been calling for arrests, if they get their wish they should prepare to see defense attorneys expose every sensitive piece of information they can get their hands on regarding Jackson's drug use and any other unhealthy habits.
"The trial will be more of an autopsy than the autopsy," Levenson tells PEOPLE. "The defense attorneys will have to scrutinize every aspect of Jackson's life and his family's life."
Doctor CooperatingLevenson adds that internally the case will be considered a homicide investigation simply because homicide investigators handle cases in which the victim died in the presence of another person – in this case, Jackson physician Dr. Conrad Murray.
Murray is cooperating with authorities, says a rep for his attorney, who declined further comment citing "our agreement with L.A. investigators."
"The bottom line is they will call it a homicide investigation until they determine it's not," Levenson says. "But I don't think anyone has evidence of a premeditated killing. That was just the family being sad about what happened."
Another Prescription Drug CaseProsecutors could also follow the blueprint established by the Anna Nicole Smith case. Prosecutors charged Stern, Smith psychiatrist Kristine Eroshevich and physician Sandeep Kapoor with the felony of conspiring to use fake names to prescribe vast amounts of potent drugs to an addict. The three have pleaded not guilty.
"That is a perfect example," says Los Angeles criminal defense attorney Robert M. Bernstein. "If drugs are involved in Michael Jackson's death, I predict you will see similar charges."
Prosecutors could also review whether any doctors violated California's health and safety code by over-prescribing not for a legitimate reason. "That is a criminal charge," says Bernstein, "and is punishable by prison."
With reporting by SARA HAMMEL and ANNE LANG