Now that the legal experts and medical experts have all weighed in and a jury has convicted Dr. Conrad Murray of involuntary manslaughter, the question still arises. Was he really guilty or wasn’t he? For me as a practicing physician, someone who every day considers how my interventions will affect my patients, there was never a real doubt to Murray’s guilt.

Here’s why: Though my license to practice medicine provides me a wide range of options from performing surgery to administering medical treatments, at the same time I am taught from the first day of medical school that if I employ a method that I am not really trained to use and directly endanger the life of my patient, then I may be guilty not only of malpractice, but also assault and battery if the patient lives, and manslaughter if he dies.

Murray was Jackson’s primary physician. He was responsible for the King of Pop’s medical care. He presided over a monstrous daily cocktail of pills and injections that appeared to have had no real medical indication. On top of that he injected an anesthetic, propofol, which works quickly and dramatically and can easily cause a patient to stop breathing.

In more than two decades of medical practice both inside the hospital and out, I have never even seen a non-anesthesiologist administering propofol, let alone in a patient’s home without proper monitoring equipment.

The nuances of this dangerous drug being improperly administered by someone unskilled in the administration were argued extensively throughout the trial. What is still left to be said is what a disturbing departure Murray’s behavior was from the essential role of being a physician.

Murray was engaged in criminal activity not only in a legal sense but also from the point of view of what a real doctor is supposed to be doing and thinking at all times.

Consider the oath of Maimonides: The eternal providence has appointed me to watch over the life and health of Thy creatures. May the love for my art actuate me at all times; may neither avarice nor miserliness, nor thirst for glory or for a great reputation engage my mind; for the enemies of truth and philanthropy could easily deceive me and make me forgetful of my lofty aim of doing good to Thy children.

In a certain sense, we physicians needed Murray’s conviction as much as the Jackson family must have needed it.

The jury's verdict serves as a brusque reminder to us not only of our limitations and what is appropriate or inappropriate for a doctor to do, but it also draws a solid line in the sand. Step over that line, and you are not only faced with a monetary concern, you could also end up in jail.

As I am teaching my students about the qualities that I think a good doctor should possess -- compassion, caution, comprehensive understanding, I also try to teach them about who they should not to be. Driven by avarice, unmindful of limitations and unaware of the power of the treatments he gives.

In Dr. Murray’s case, there appears to have be the worst combination of all these traits and the most blatant disregard for medical professionalism and human life.

At a time when our daily roles as doctors are under assault on all sides from insurance and government and legal fears, it is a good time for us to take a step back and reflect on who we are and who we want to be as physicians.

Dr. Murray is the antithesis of my view of a physician. When he drew up that last fatal dose of propofol, he not only sealed his own fate he also instantly became the model for the person everywhere that doctors do not want to be.

Marc Siegel, M.D. is a professor of medicine and Medical Director of Doctor Radio at NYU Langone Medical Center. He is a member of the Fox News Medical A team and the author several books. His most recent book is "The Inner Pulse; Unlocking the Secret Code of Sickness and Health."