The panel is set to question BP and Transocean officials, as well as technicians responsible for alerting rig workers when gas levels may be too high in drilling mud.
Three days of hearings were to begin Tuesday at an airport hotel in Houston before the joint U.S. Coast Guard-Bureau of Ocean Energy Management, Regulation and Enforcement panel.
It's the panel's sixth series of hearings, and at least one more is expected after this one before the panel issues its report, which is due by March 27. The panel is still awaiting the results of forensic testing on a key piece of evidence - the blowout preventer that failed to stop the spill. Investigators are analyzing it at a NASA facility in New Orleans.
Besides issuing conclusions on the cause of the explosion, the panel also was expected to make recommendations on how to improve regulation, safety and oversight.
Other federal agencies, commissions, members of Congress and the companies involved have been investigating the circumstances of the April 20 explosion aboard the Deepwater Horizon rig, which killed 11 men and led to more than 200 million gallons of oil spewing from BP's undersea well.
However, this panel's inquiry, which began in May, has been among the most exhaustive and has included sworn testimony from dozens of key officials, rig workers and contractors.
Subsequent proceedings will examine the recovery, examination, analysis and evaluation of the blowout preventer.
Testing on the device began Nov. 16, more than two months after the 300-ton device was raised from the seafloor.
Witnesses expected to testify at the hearings that were to begin Tuesday and run through Thursday include a BP drilling engineer manager and several Transocean officials.
The panel also was expected to hear from two technicians known as mud loggers who use an assortment of electronic instruments to monitor the drill bit for traces of oil or gas and check for concentrations of hydrocarbons in the drilling mud, and notify rig personnel when levels are too high. Hydrocarbons, a mixture of hydrogen and carbon, are found in crude oil.
Deepwater Horizon Joint Investigation: http://www.deepwaterinvestigation.com
BP PLC: http://www.bp.com/