A judge in Alabama has delayed the reckless murder trial of a former NASA astronaut charged in a crash that killed two girls four years ago, court records show.

Former space shuttle commander James Halsell of Huntsville was set to go on trial Monday.

But the defense requested a postponement citing the death of the father of lead attorney Jim Sturdivant, and a judge agreed in an order filed Sunday.

No new date was set.

Halsell, 63, was arrested after a car crash killed two sisters, 11-year-old Niomi Deona James and 13-year-old Jayla Latrick Parler, in 2016 and severely injured their father and a woman. Authorities contend he was under the influence of alcohol, but the defense blames the wreck on sleeping medication.

Halsell, who is free on bond, flew five shuttle missions before retiring from NASA in 2006 with more than 1,200 hours in space. He worked in the private aerospace industry before the crash.