The bus, which wasn't on its designated route in Chattanooga, Tennessee, didn't drop off any children in front of their homes that afternoon.

Instead, it swerved off a street, toppled on its side and slammed into a tree, killing six children and injuring more than a dozen others.

On Tuesday, Walker made his first court appearance since the November 21 crash. After the judge granted a request to continue the hearing on December 15, Walker's attorney spoke publicly for the first time.

"Obviously this has been a devastating tragedy for the Chattanooga community. There are families in mourning, there are families that are still dealing with loved ones in the hospital in intensive care," attorney Amanda Dunn said.

"Mr. Walker's family is also devastated by this tragedy. Mr. Walker has been devastated," she added. "We're hopeful that the investigation can conclude quickly and we have a better understanding of what occurred last Monday."

Here is what we know about him so far.

What he's charged with

Walker faces five counts of vehicular homicide, as well charges of reckless endangerment and reckless driving. A sixth vehicular homicide charge likely will be added, a police spokeswoman said last week.

The bus wrapped around this tree upon impact.

According to the court affidavit, the charges were brought "because of the reckless nature of Mr. Walker's driving, combined with his very high speed and weaving within his lane."

Walker's family says the crash was a terrible accident

Moments after the catastrophic crash Monday, Walker called his mother and told her what happened, she told CNN.

"'Mama, I love you. I have been in a drastic accident,'" Cook recalled her son saying. "He texted me minutes later saying the kids are dead."

Chattanooga Police Chief Fred Fletcher said Walker called his mother, but did not appear to have dialed 911.

His mother says he had never been in trouble

Cook said Walker is a respected man and the father of a 3-year-old son.

"He is a marvelous son. For two years he worked two jobs. He's never been in trouble before," his mother said.

"He is a respected young man, grew up in Chattanooga and is liked by everyone."

Walker had a second job

JUST WATCHED Bus crash 911 call: 'I can see an arm moving' Replay More Videos ... MUST WATCH Bus crash 911 call: 'I can see an arm moving' 01:41

Last week, the NTSB said that it was looking into what role Walker's second job at Amazon may have played in the fatal bus crash.

Amazon provided some information on his employment to CNN.

The company confirmed that Walker was a fulfillment associate with Amazon at the Chattanooga Fulfillment Center. His "last shift was an overnight shift Saturday," the company said.

A co-worker at Amazon told CNN affiliate WSMV-TV that Walker worked two jobs to take care of his son.

"The picture that you paint of someone who'd do something like this is not the vibe I got from him," the colleague told the station. "He was respectable, just a very nice person."

She added that he'd often come to work tired.

Officials say Walker was speeding

Police Sgt. Austin Garrett said no traces of alcohol or drugs were found in Walker's blood.

But investigators allege that Walker was driving "well above" the speed limit.

"Mr. Walker lost control of the bus and swerved off of the roadway to the right, striking an elevated driveway and mailbox, swerved to the left and began to overturn, striking a telephone pole and a tree," according to an arrest affidavit for Walker.

Talley Rd bus crash update: Results are back from blood test on school bus driver. No evidence of drugs or alcohol in blood per #TBI test. — Chattanooga Police (@ChattanoogaPD) November 23, 2016

There had been complaints about his driving

Walker's driving had alarmed students, parents and faculty in the weeks leading up to the accident, according to complaints obtained by CNN.

A principal twice expressed concern over the speed at which Walker had driven out of the school parking lot. Students claimed he was trying to injure them. And a parent, responding to complaints Walker had cursed at children and tried to hurt them with his driving, threatened to beat up the bus driver, the records allege.

Six students had told school employees the driver was swerving and "purposely trying to cause them to fall," the principal said.

According to school records, at least two students wrote letters to officials expressing concerns for their safety. One student claimed the driver "was doing sharp turns and he made me fly over to the next seat." A second student said the bus felt like it would "flip over" given how fast it traveled.

Walker complained to officials that, throughout the fall, students failed to heed his safety instructions. He said he tried to reason with students, to no avail.

Walker reported some student misconduct to school officials, saying students were facing the wrong way on the bus, standing on their seats and goofing around while the bus was in motion.

After Walker grew frustrated one day, the driver said "he did not care about the students and proceeded to tell the students he did not care about them," a school system staffer recalled.

When asked Tuesday about the complaints against her client, Dunn responded, "I don't have any further comment on those complaints."

Walker had been in another accident recently

The accident was the second time in two months that Walker crashed a school bus.

In September, Walker was driving around a blind curve in a residential area when he failed to yield the right of way and sideswiped another car, according to the accident report.

CNN Map

In the earlier crash, which Garrett described as a "minor wreck," Walker "crossed over into the oncoming traffic lane to maneuver the bus through the curve and struck vehicle No. 2 in doing so," the report states. "There were no children in the front rows, and no reports of any injuries. The damage (was) minor to both vehicles."

Walker received his commercial driver's license in April, the NTSB said.