TULSA, Oklahoma - The medical examiner in Tulsa has the body of Clayton Lockett for a full autopsy that will determine how much of the execution drugs actually made it into his system.

That's unknown, because of what prison officials said was a blown vein, which is a common medical complication.

"It is not unusual, it happens every day, even for the most proficient of IV starters, they might have a vein blow on them," said Michael Baker, EMS Director for Tulsa Fire.

With demonstration arms, complete with veins, he showed us how either a medical mistake, or a person's anatomy, could cause a vein to blow out. When that happens - the medication goes into the tissue - not the blood - and the drugs have little or no effect.

"Everybody's anatomy is different. Some people have large veins that are visible that we can easily get in, or ones that are more fragile," Baker said.

At the prison, it was the medical issue of a blown vein that prison officials say caused them to stop the procedure.

That was after the inmate continued to move and mumble long after he would have been expected to have died.

Robert Patton, DOC Director, said, "There was some concern at that time that the drugs were not having an effect, so a doctor observed the line and determined that the line had blown."

Baker said it's possible the needle going in passed through the artery - a problem called a double puncture.

He said while it can happen to anyone, but an experienced person should notice the problem quickly - and without question - if that's the problem - the medication isn't getting where it's supposed to be.

"They may not have even known at the point, they might have had indicators that everything was fine; it's just a complication of the procedure," Baker said.

It's just like a tube, it's going to leak, and that could have been exactly what happened.

The blood work from an autopsy can take several months to complete, and that is just one level of the investigation into what happened.