NASHVILLE, Tenn. (AP) — The driver in a Chattanooga school bus wreck that killed six children last week has declined to be interviewed by federal crash investigators on advice of his lawyer, the National Transportation Safety Board said Thursday.
The NTSB has filed subpoenas to obtain 24-year-old driver Johnthony Walker's medical and mental health history. Investigators are also seeking his cellphone records and employment details from his second job with Amazon. The agency's final report is expected to be presented within 18 months.
The six children died on Nov. 21 after the bus carrying 37 students hit a mailbox and utility pole, rolled onto its side and then crashed into a tree.
Walker's attorney, Amanda Dunn, has said she expects him to plead not guilty if a grand jury indicts him for vehicular homicide.
Walker was working for school bus contactor Durham School Services, which is paying his legal bills.
Durham CEO David A. Duke said in a video released Thursday that the company is making multimillion-dollar safety changes after the crash.
Duke said Durham will put in place a nationwide complaint management system where teachers and administrators can report specific issues with drivers and buses. It will be online immediately in Chattanooga and across the country for Durham by the end of next year.
The company will also install cameras in all buses that record the driver and the road each time they sense unusual driving. They'll be installed on Chattanooga buses by the end of the year and on all buses within the next two years.
Duke said the company's own investigation into the accident is ongoing.
The Hamilton County school district last week released a correspondence from students, parents and administrators raising concerns about Walker's behavior behind the wheel of the bus in the weeks before the crash.
Duke told the Chattanooga Times Free Press that his company searched its email database and only found a handful of complaints. After someone complained Walker had been speeding, the company checked GPS data on the bus and found that it wasn't the case, Duke said.
"We can only act on what we know and what's before us," Duke told the paper.
Duke has said the company is cooperating with law enforcement and federal crash investigators. That cooperation pledge doesn't extend to Walker, for whom the company has hired his own independent lawyer.
"We are not privy to the advice that the counsel is providing Mr. Walker," Durham spokeswoman Molly Hart said.
Associated Press writer Jonathan Mattise contributed to this report.