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OKLAHOMA CITY –  A preliminary autopsy report gives a better idea of what went wrong during a botched execution of an Oklahoma inmate earlier this year.

On April 29, Clayton Lockett was scheduled to die by lethal injection.

After being injected with a lethal injection drug cocktail, Lockett was conscious, moving and talking throughout the process when he should have been unconscious.

After nearly 45 minutes, Lockett was pronounced dead after suffering a massive heart attack.

Click here for more information on Lockett’s execution.

An independent autopsy was ordered by Lockett’s attorney to determine exactly how Lockett died and what went wrong during the execution process.

According to preliminary findings by forensic pathologist Dr. Joseph Cohen, it wasn’t the new drug mixture that caused the execution to go wrong.

Instead, the report claims the execution team did not set up a properly functioning IV in Lockett’s femoral vein.

It claims the IV nicked Lockett’s vein and the drugs were actually absorbed into his muscle.

The report states Lockett’s veins were in excellent shape “for the purpose of achieving venous access” and were easily seen.

According to the report, there were “skin punctures on the extremities and right and left femoral areas,” meaning the team tried to set IVs in both arms and both sides of Lockett’s groin.

The execution team set up the IV in his femoral vein, which is riskier and more difficult to place.

Cohen states he found superficial and deep hemorrhages, meaning the needle only pricked the femoral vein.

Following the botched execution, officials said Lockett’s veins collapsed.

However, the report says that was not the case.

Instead, it claims the IV was improperly placed and ineffective in Lockett’s femoral vein.

Cohen also said it was unlikely that dehydration played a role in compromising the execution.

Dr. Cohen says there are other pieces of information he needs to fully complete the report, including medical examiner reports, medical records and information on injuries.

The state has ordered an independent review of Lockett’s execution, seeking a separate autopsy from the Dallas medical examiner.

At this time, those findings have not been released.