According to CNN, this is the timeline of drugs he received on the day he died:

1:30 am.: 10 mg Valium

2 am:  2 mg IV Ativan

3 am: 2 mg IV Versed.

5 am: 2 mg of IV Ativan.

7:30 am: 2 mg of Versed; placed on pulse ox (measures amount of oxygen in blood-- used in these cases when you worry they may be too sedated to breathe)

10:40 am: "after repeated demands/requests from Jackson," Dr. Murray administered 25 mg of propofol.

I.

We can say that this is enough drugs to kill a horse, but look at 5am: Jackson is still awake.  And at 7:30.  And at 10:40.  It may seem like a lot of drugs to you, but regardless, they were too weak to put him down.  Therefore, you can't say these were lethal levels of medications; half a bottle of rum is lethal to some people.

So when CNN does that idiotic segment where they give a reporter propofol to show how strong it is, you should take that for what it is: pornography.


II.

Farily safe to assume: this isn't the first time Jackson's taken these drugs, at these doses.

III.

It's extremely unusual for a doctor to be charged criminally in such cases, unless there was malice; they are usually dealt with in civil court (malpractice) and/or by a medical review board.

It is going to be impossible for a prosecutors to prove, beyond a reasonable doubt, that Dr. Murray killed Jackson.

• First, the amount of drugs Murray administered was not only not lethal-- it wasn't even effective.  Jackson was wide awake, all night.
• That amount of benzodiazepine drugs is not at all unusual for a benzo addict.  If Jackson was used to that amount, it's going to be very hard to show why that amount, on that day, killed him.
• Which brings us to the second point: we have no way of knowing whether Jackson was giving himself extra oral, or even IV doses of the same drugs, that Murray didn't know about.   Apparently, Jackson had 8 other bottles of propofol in the house, along with other Ativans, etc.  It wouldn't be surprising if Jackosn was taking extra Valiums throughout the night.
  
• Third: "What about the propofol?  The coroner said high blood levels of propofol killed him."  If the coroner said this, he is a fool. Picking out one drug as the cause of death is like blaming one section of the ocean water for a drowning.   The effect of propofol only lasts 5-10 minutes. If it was a single injection, it would have stopped working after that long.  Propofol rarely accumulates to high blood levels because it clears so quickly; a high level would suggest either supplementation, or Murray was lying.  Then the prosecution's case falls apart: either Murray told the truth about the 25mg, and therefore Jackson was supplementing; or he was lying, which... good luck proving that.
• Unless Dr. Murray gave him a propofol drip and forgot to turn it off.  That would be...
  
• In any event, unless you give a high dose all at once, in order to die you would have to maintain the propofol infusion, i.e. not turn it off.  That wouldn't be negligence, that would be retardation or murder.   But that would be the only way propofol could have killed him. 
• Fourth: administering propofol along with benzodiazepines is not unheard of, nor is using it outside a hospital with nothing more than a pulse ox. (e.g. used commonly in a doctor's office for a colonoscopy.)

IV.  There is one way this could be an easy case of negligent homicide: if Dr. Murray administered the propofol but, contrary to what Dr. Murray said, he didn't have any monitoring equipment.  This is the part of the story that makes no sense to me.  A pulseox is a simple machine to measure blood oxygen levels, you clip it on the patient's finger and watch the readout display numbers from 0-100%

In order to die, you must first fall asleep, and then your breathing slows and stops. This takes minutes, not seconds.   Wasn't it on after Jackson fell asleep?  If so, why didn't Murray hear the first alarm that goes off when the oxygenation fell below a certain, non lethal level?  Did he have it off?

It seems crazy to me that you would have a pulseox, put it on the patient, but ignore the readout for the crucial hour after the guy falls alseep?  Especially after all those benzos?

Of course, having a pulse ox to detect low oxygenation is pointless if you don't have supplemental oxygen on hand.

The simple explanation is that he either didn't use the pulse ox (negligence) or he did use it but paid it no mind (negligence and stupidity); or he did use it, heard the alarm but was unable to save Jackson despite his attempts.  This is all assuming he did give only a single injection of propofol, not a propofol drip. 

Murray says he did administer CPR and flumazenil (the antidote for benzos, but not propofol) but the timeline is hazy. Maybe Murray was scared of getting in trouble, so he lied about the times; but if he did use the pulse ox and diligently tried to save him, then there's really no criminal case here.

V.

A small clinical aside, I neither expect Dr. Murray to know this, or even the majority of the doctors.  There's a difference between time of onset and peak blood level.  Just because the pill doesn't work in 30 minutes, doesn't mean there isn't another 70% of the pill coming in an hour.

This is how famous people die: they take stimulants to party all night, and sleep very little.  Finally, on day 3 they're too wired to fall asleep naturally, so they take a few extra sedatives (because they feel so wired.)  However, the full dose of the pills doesn't happen until after they fall asleep; the sedation is worsened even further by stimulant withdrawal; and, of course, the natural exhaustion that comes with partying for three days and not sleeping.

Smaller doses, more time.  That's the secret to not being ruled a suicide.