RICHMOND, Va. -- The National Transportation Safety Board has released hundreds of documents in its investigation into a bus crash on Interstate 95 in Virginia that killed four people and injured dozens.

The bus bound for New York overturned about 30 miles north of Richmond on May 31, 2011.

Court records show driver Kin Yiu Cheung admitted to police that he fell asleep at the wheel. He is set to go to trial later this month on four counts of involuntary manslaughter. Dispatcher Zhao Jian Chen is set to face the same charges in October.

The docket includes about 630 pages of interview summaries, investigative reports, more than 65 photographs and other documents.

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