The official in charge of overseeing the risks of BP's offshore Gulf marine operations said Monday that he rarely had contact with a key manager at the company that owned the rig that exploded, causing a massive oil spill.

Neil Cramond testified before an investigative panel in Houston looking into the cause of the Deepwater Horizon explosion of April 20 that killed 11 workers and set off the spill.

Cramond said he rarely communicated with Paul Johnson, identified by the panel as rig manager for Transocean, the company that owned the rig. Johnson's role on the Deepwater Horizon was not immediately specified. He was scheduled to testify later Monday.

Cramond also testified that captains of rigs such as the Deepwater Horizon are ultimately responsible for crew safety and environmental matters, but are not always involved in decisions about how to deal with drilling operations and potential risks.

Members of the joint U.S. Coast Guard-Bureau of Energy Management, Regulation and Enforcement investigative panel pressed hard on communication between BP officials on shore and the people operating its rigs at sea.

They also questioned communication between BP, Transocean and other entities involved in operating the rig and overseeing maintenance. The hearings will continue through Friday.