An official report released Thursday about a bungled execution in Oklahoma in April says that an improperly placed intravenous line in the prisoner’s groin allowed the drugs to perfuse surrounding tissue rather than to flow directly into his bloodstream.

The report was ordered by Gov. Mary Fallin after the prolonged writhing and gasping of the prisoner, Clayton D. Lockett, during an execution that drew global attention to death penalty procedures and problems associated with lethal injections.

Because the groin area was covered with a sheet as the injections began — first a sedative intended to render Mr. Lockett unconscious, and then paralyzing and heart-stopping agents — the doctor and paramedic on the scene did not see the bulge, larger than a golf ball, indicating a procedure gone awry, said the report by Michael C. Thompson, the commissioner of public safety.

The report, which described prison officials as ill-prepared for unexpected events during an execution, recommended keeping injection sites visible at all times, improving the training of prison officials who inject the lethal drugs and developing procedures for emergency situations.