An autopsy arranged by lawyers for an Oklahoma inmate who died following a botched execution says he had healthy veins but his body had punctures from multiple attempts to tap them.

Pathologist Dr. Joseph Cohen said more information was needed to determine why Clayton Lockett died. Oklahoma officials have said it appeared Lockett didn't receive a full dose of three lethal drugs, perhaps after a vein collapsed.

Cohen said Lockett had good veins. He said it appeared the execution team failed repeatedly while inserting an intravenous line.

After Lockett struggled, the execution team discovered a problem with the IV. Officials halted the execution, but Lockett died shortly afterward. Results from a state autopsy are pending. Toxicology reports haven't been issued, so it's unclear how much of the drugs Lockett received.