(CNN)The bus driver on trial for his role in the death of six elementary school students said in court Wednesday that the fatal crash occurred after he veered away from a white vehicle that was encroaching into his lane.
School bus driver in fatal crash testifies: "I chose to veer out of the way"
"I chose to veer out of the way," Johnthony Walker said. "I figured I had gotten out of the way of the other vehicle and our route would continue."
But his decision proved to be fatal. The bus, carrying 37 students from Woodmore Elementary School in Chattanooga, Tennessee, flipped over and crashed into a tree in November 2016, leaving six children between the ages of 6 and 10 dead.
Prosecutors argued in court that Walker was driving well over the 30 mph speed limit and was on his phone when the school bus swerved off the street.
"It all could have been avoided if Johnthony Walker had slowed down and gone the speed limit and stayed off his phone," prosecutor Crystle Carrion said, according to CNN affiliate WTVC.
However, in his testimony on Wednesday, Walker said he was not on the phone at the time of the crash and that he did not remember how fast he was going.
Walker has been charged with six counts of vehicular homicide, as well as four counts of reckless aggravated assault, one count of reckless endangerment, one count of reckless driving and one count of use of a portable device by a bus driver. He pleaded not guilty to negligent homicide charges, according to WTVC, in March 2017.
The prosecution and the defense rested on Wednesday after two days of testimony.
Walker's attorney Amanda Dunn said on WTVC that Chattanooga police didn't investigate the case properly. She says they didn't interview witnesses at the scene and jumped to conclusions rather than letting facts develop.
Dunn said as Walker was driving the bus, a white "transport type of vehicle" was driving in the opposite direction and came around a curve in the road going into the same lane as Walker's bus.
"There was never an investigation about the white bus, there was never any attempt to take evidence from the roadway or speak to any eyewitnesses about this white bus," Dunn said. "There was never an investigation on any of the facts that would have led to a conclusion other than the one the Chattanooga Police Department had already made about Johnthony."
During her cross-examination of Chattanooga Police Investigator Joe Warren, Dunn asked about his investigation methods.
"If I was going on only tire marks, that'd be one thing, but there are other indications that speed was a factor," Warren said.
He said in December 2016 he estimated the speed of the bus at between 50 and 52 mph, about 20 mph above the posted speed limit.
Other witnesses at the scene, such as state witnesses Ann Jones Pierre and Michelle Brogdon, said Walker was going fast.
"He left the stop sign a little fast," Pierre said. She lives in the neighborhood where the crash took place and was driving behind Walker's bus before the crash, WTVC reports.
"You could tell he was going over the speed limit," Brogdon said. She lived near the crash site, according to WTVC, and rushed to the scene when she heard the crash.
In addition, investigators discovered that Walker wasn't driving on his designated route when the crash took place. However, in court on Wednesday, Walker said that older drivers gave him a route sheet, but that the route had since changed as certain students had been added or taken off the route.
Prosecutors said Walker was on the phone with Takiesha Nixon for four minutes before the bus crash. The two work together at Amazon, Walker's second job.
Nixon said as soon as she learned Walker was driving a bus during their phone conversation, she hung up. Dunn said during Nixon's cross-examination that she didn't know Walker was involved in the crash until much later.