About 11 hours before the Deepwater Horizon exploded, a disagreement took place between the top manager for oil giant BP PLC on the drilling rig and his counterpart for the rig's owner, Transocean Ltd., concerning the final steps in shutting down the nearly completed well, according to a worker's sworn statement.

Michael Williams, a Transocean employee who was chief electronics technician on the rig, said there was "confusion" between those high-ranking officials in an 11 a.m. meeting on the day of the rig blast, according...