NEW YORK (CBSNewYork) — Authorities were still trying to determine what led to this weekend’s horrific bus crash in the Bronx. Federal investigators were talking to the driver on Tuesday.

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Investigators at the scene of the crash (credit: CBS 2)

“We’re hearing so many stories, conflicting oftentimes, and we need to get to the bottom of that,” said Christopher Hart, NTSB Vice Chairman.

Federal investigators were focusing on what the driver was doing in the three days leading up to Saturday’s accident.

“We’ll want to know what he ate, what he drank, how much he slept, everything we can find out about the driver in the 72 hours prior,” Hart said.

Much more was already known about the driver’s background in the three days following the accident. Ophadell Williams, 40, had several convictions on his criminal record, including driving with a suspended license in 2003, grand larceny in 1998 and a manslaughter conviction in 1992.

In his initial statements to investigators, Williams said he was clipped by a tractor trailer while returning from the Mohegan Sun Casino, causing him to lose control and the bus to skid into a highway sign post.

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The post sliced the top off the bus and killed 15 passengers.

Even as his friends were raising the possibility that Williams may have dozed off, they said if he did, he was probably working overtime to support his family.

“He’s scared to death man, you know? He’s crying cause, you know, he hurt some people,” said Mel Davis, Williams’ friend.

Gov. Andrew Cuomo has ordered an investigation into how Williams was able to hold a commercial driver’s license while he had a criminal record.

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