James Halsell Jr was indicted on two counts each of reckless murder and assault by a grand jury in Alabama.

The ex-astronaut from Huntsville, who turns 60 on Friday, was arrested after the deaths on June 6 of 11-year-old Niomi James and 13-year-old Jayla Parler in Tuscaloosa, west Alabama.

Police reports showed that investigators believe alcohol and speed could be factors, and the girls were ejected from the car they were travelling in, according to troopers.

The reckless murder charges involve the girls' deaths, said county prosecutor Jonathan Cross.

The assault charges stem from injuries suffered by the girls' father, Pernell James, who was driving, and his friend Shontel Cutts.

The girls' relatives filed two civil lawsuits blaming Halsell for the deaths.

Halsell's attorneys filed a document in one of those cases saying the driver of the car carrying the girls failed to yield and contributed to the wreck.

The girls' father told investigators he was driving about 65mph on US 82 when a car travelling "at a very high rate of speed" struck his Ford Fiesta from the rear, crushing the Ford and sending it tumbling across the road, said court documents.

Halsell was driving a rental car at the time and told officers he thought he was on Interstate 20/59, not US 82, according to a sworn statement by a state trooper.

Halsell was driving to his native Louisiana to pick up his son and was so intoxicated that he asked to see the victims' bodies, said the troopers' statement.

The girls lived with their mother in Houston and their father, Pernell James of Brent, was returning home from Texas with them and a woman for a summertime visit, according to Brent mayor Dennis Stripling.

Court documents do not indicate that Halsell mentioned his career to officers, and a trooper spokesman said authorities did not realise he was a former astronaut until they saw news reports about the case.

Halsell's career with the space agency included five shuttle flights starting in 1994, said an online biography by Nasa.

He spent more than 1,250 hours in space, serving as commander on three shuttle missions and pilot on two others.

Halsell helped lead Nasa's return-to-flight effort after the 2003 disaster involving the space shuttle Columbia in which all seven astronauts died.

He retired in 2006 and worked for at least two aerospace companies afterwards, including ATK Launch Systems, Utah, according to his Nasa biography.