JACKSONVILLE, Fla. — The story of the cargo ship El Faro’s final hours was reconstructed using thousands of pages of public documents, hours of testimony before the U.S. Coast Guard’s investigative board and interviews with crew family members and maritime experts.

The most important source material for the story was the final conversations of the crew. In December, the National Transportation Safety Board released data from the El Faro’s voyage data recorder.

That small machine held more than 20 hours of audio captured by microphones embedded in the El Faro’s bridge, where the captain and crew fought desperately to save the ship as it sank after losing propulsion while sailing through a Category 3 hurricane. All 33 aboard died.

The NTSB identified the speakers in the transcript only by their professional titles. In some cases, like the captain, determining the identity was easy. For others, like helmsman Frank Hamm, it was more difficult. Hamm was among a group of able-bodied seamen on the vessel, so The Associated Press relied on Hamm’s family and clues in the transcript to identify him.

The testimony of officials from the ship’s owner, TOTE Maritime Inc., and El Faro crew members who weren’t on the ship’s final journey was also an important source. Most testified before the Coast Guard Marine Board of Investigation over the past year in Jacksonville.

For example, whether Capt. Michael Davidson, of Windham, Maine, knew prior to setting sail that he had not been selected by TOTE to lead one of the company’s new ships was discussed by multiple witnesses. Former El Faro chief mate Jamie Torres testified that Davidson knew he’d been passed over and was disappointed. The master of the El Faro’s sister ship also testified that Davidson knew he’d not gotten the job and was unhappy about it.

Information about incorrect weather data sent to the ship came from executives of Applied Weather Technology, provider of the ship’s Bon Voyage weather program. They testified the El Faro had received old storm data early on in the trip. Bon Voyage was the program Davidson usually used to track weather, and he refers to it in his comments in the recorder transcript.

Background information for crew members Danielle Randolph, Steve Shultz and Frank Hamm was provided by family members, posts by the crew members on their Facebook pages, transcripts of private interviews between family and NTSB investigators, and Coast Guard testimony. Davidson’s widow did not respond to multiple requests for interviews from the AP.