A former Alabama Space Shuttle commander will spend at least four years in prison after pleading guilty to manslaughter and assault in the death of two young girls. 

James Halsell Jr., 64, pleaded guilty to two counts of manslaughter and two counts of assault in the deaths of Niomi Deona James, 11 and Jayla Latrick Parler, 13, nearly five years after the crash.

The young girls died in June 2016 after Halsell's car collided into their vehicle at 100 miles per hour and threw them off from the vehicle, according to Tuscaloosa authorities.

According to reports, the family had just picked up the girls from Texas for summer vacation with their father and were almost home when the crash occurred. Halsell was said to be on his way to pick up his son in West Monroe.

Before driving off, Tuscaloosa County District Attorney Hays Webb said Halsell had consumed a bottle of wine and had taken sleeping pills.

Authorities asserted Halsell, who went to work in the aerospace industry after leaving NASA in 2006, was intoxicated.

But his attorney blamed the accident on sleeping medication, which Jim Sturdivant, Halsell's lawyer, said was the "main cause of the tragic sequence of events that occurred that night," the Birmingham Real-Time News reported.

While he could have been sentenced to 20 years for each charge of manslaughter and 10 years for each charge of assault, a judge agreed to probation and ordered the former astronaut to spend four years in prison without early release followed by 10 years of supervised release, the Associated Press reported.

Halsell apologized in court and was taken into custody immediately after the proceeding. Outside the court premises, Latrice Parler, the girls' mother, said relatives were not pleased with the decision, AP said.