After Dr. Steve Shafer, a top expert in the anesthetic propofol, raked Conrad Murray over the coals, Wednesday, he also undercut the defense's theory that Michael Jackson had self-administered powerful anesthetic propofol to death on Thursday, Oct. 20.

Shafer testified that the level of of propofol found in the star's bloodstream at the autopsy was too high to be explained by the self-administration theory, which was proved as a crazy scenario.

In the previous testimony, Murray admitted that he gave propofol to the singer as sleep aid on the day of his death, however, he said it's only a small quantity of the drug, which never threatened Jackson's life. Actually the King of Pop regarded the drug as milk and took the lethal dose by himself, which led to his sudden death.

However, the top anesthesiology expert never agreed this theory, saying that if the theory makes sense, the pop icon would have had to self-administer several times to accumulate the amount of the propofol in his bloodstream.

People don't wake up ... hellbent to give themselves another dose, Shafer said. It's a crazy scenario.

According to Shafer, even though the patient had already stopped the breathing because of the overdosed propofol, his heart can still beat for 10 minutes and circulate blood.

Accordingly, supposing Jackson self-administered propofol as much as 100 milligrams six times and stopped breathing at last shot, but his heart would still beat long enough to lower the propofol concentration below the level found in the bloodstream at autopsy, Shafer said.

The expert also demonstrated in court how Murray could have used a simple but deadly IV infusion of propofol to administer the drug into a vein in Jackson to help him sleep.

According to Shafer, it's important the anesthetic to drip at a set rate. However, Murray did wrongly without a pump to control the flow. He is responsible for every drop of propofol in that room, Shafer said.

Also, the expert undercut defense's another theory that the star swallowed a fatal number of sedative lorazepam pills.

According to the medical examiners, the propofol was the main cause of Jackson's death, and the sedative lorazepam played a contributing role.

Shafer said the amount of lorazepam found in the singer's stomach was minuscule. The results ... prove that Michael Jackson did not swallow lorazepam, Shafer testified.

About the theory that Jackson guzzled the propofol by himself, Shafter said some studies showed that propofol is not fatal when swallowed.

If convicted, Murray could serve a sentence of up to four years in prison and also lose his medical license.