In a teleconference Monday, Cmdr. Theresa Hatfield estimated that the investigation of the disabled ship would take six months.
She said the Bahamas is leading the investigation, with the Coast Guard and National Transportation Safety Board leading U.S. interests in the probe.
She said investigators have been with the ship since it arrived Thursday in Mobile, and interviews have been conducted with passengers and crew.
The ship left Galveston, Texas, on Feb. 17 for a four-day trip to Mexico. The fire paralyzed the ship early Sunday, leaving it adrift in the Gulf of Mexico until tugboats towed it to Mobile.