The truck driver who caused a chain-reaction accident that killed 10 people had a clean record when his commercial license was renewed three months before the crash.

Investigators are still trying to figure out why Donald Creed didn't stop, and perhaps didn't even hit the brakes, before his big rig slammed until a line of cars on an Oklahoma turnpike.

Four of the dead are from Texas, including a suburban Dallas husband, wife and child and the wife's mother.

A National Transportation Safety Board team was en route to Oklahoma Monday to investigate the turnpike accident.

A prosecutor says Creed, 76, could face as many as 10 misdemeanor homicide charges, each carrying a one-year jail sentence.

The death toll from Friday's crash climbed to 10 Sunday after Frisco, Texas, resident Shelby Hayes died at a Joplin, Mo., hospital.

Hayes; her husband, Randall; their 7-year-old son, Ethan, and her mother, Cynthia Olson, were driving to a funeral in Sarcoxie, Mo. when the crash occurred.

The others were pronounced dead at the scene.

Randall Hayes' mother, Wanda, said she was with Shelby Hayes when she died Sunday morning.

Wanda Hayes said she's working to get her son and grandson back to Garland so funeral arrangements can be made.

Crash Victims

Ethan Hayes, 7, Frisco, Texas
Randall Hayes, 38, Frisco, Texas
Shelby Hayes, 35, Frisco, Texas
Antonio Hooks, 42, Oklahoma City
Dione Hooks, 41, Oklahoma City
Earlene Hooks, 63, Oklahoma City
Oral Hooks, 69, Oklahoma City
Cynthia Olson, 55, Crossroads, Texas
Ernestia Reyes, age not known, Phoenix
Ricardo Reyes, 39, Phoenix