( CNN ) -- New York 's governor , citing questions about the driver 's `` criminal record and driving history , '' on Monday ordered the state 's inspector general to investigate how a Brooklyn man got licensed to drive a bus that crashed over the weekend , leading to the deaths of 15 people . The driver , 40-year-old Ophadell Williams , has not been charged . Police said Williams told investigators that the incident occurred early Saturday after he swerved to avoid a tractor-trailer that might have clipped the bus . The bus then flipped on its side and smashed into the poles , which cut through two-thirds of the vehicle . Gov . Andrew Cuomo directed Inspector General Ellen Biben to `` commence an immediate investigation '' in light of issues related to Williams ' `` criminal record and driving history . '' In a statement , Cuomo questioned why Williams was able to get and keep a commercial driver 's license . Staff from the inspector general 's office will coordinate with the New York state police , as well as the Bronx district attorney 's office , in the investigation , according to Cuomo . Williams fatally stabbed a man about 20 years ago , leading to a manslaughter conviction , said New York Department of Correctional Services spokeswoman Linda Foglia . He served three of the nine years he was sentenced , from 1992 to 1994 . He was later convicted of grand larceny , leading him to spend parts of the years 1998 to 2002 behind bars , according to Foglia . A New York City official said Monday that a 15th person had died because of injuries related to the crash , which took place in the Bronx , about 5:30 a.m. on a stretch of I-95 called the New England Thruway not far from Westchester County . The bus had left the Mohegan Sun Resort and Casino in Uncasville , Connecticut , and was bound for Chinatown in Manhattan , according to news reports . Along with those killed , at least seven of the 31 passengers suffered severe injuries and were transported to area hospitals with the remaining survivors . At least five people being treated at New York 's St. Barnabas Hospital suffered skull and spinal fractures , internal bleeding and broken bones , Dr. Ernest Patti told reporters . Williams suffered `` non-life threatening injuries , '' police said . Police recovered a tractor-trailer that was traveling through the area at the time and interviewed its driver . The driver of the tractor-trailer denied that two vehicles collided before the bus crashed , a law enforcement source told CNN . Federal investigators are considering other potential causes of the crash , including mechanical problems , steering and brake issues as well as the possibility the driver fell asleep . Some surviving passengers , according to news reports , told police that they felt the bus roll over rumble strips before the crash . At a Sunday afternoon press conference , National Transportation Safety Board Vice-Chairman Christopher Hart said investigators are looking for video recordings taken at the casino and , possibly , an electronic hotel key card that might track some of Williams ' activities within 72 hours of the accident . Investigators previously admitted they are examining Williams ' background and testing his blood for the presence of alcohol . Police officials also have said they are looking into the possibility that Williams had been speeding prior to the accident . Two UPS couriers told CNN affiliate WABC-TV that they twice saw the bus traveling very fast on the highway before the accident . In addition , records on the Federal Motor Carrier Safety Administration website show that the bus line involved -- World Wide Travel -- was involved in a crash in New York in 2009 that resulted in one injury , and a crash in New Jersey in 2010 resulting in one injury . The company has been cited five times for `` fatigued driving '' between December 2009 and October 2010 -- twice in in New Jersey , twice in Pennsylvania and once in Connecticut , records show .
Mr . Cuomo has ordered an investigation into a bus accident that left 15 dead . He cited questions about how the bus driver got a commercial driver 's license . John Williams had served time for manslaughter and grand larceny , an official says . He claims he swerved to avoid a tractor - trailer ; he has n't been charged .