Editor's note: The trial began as planned Thursday, and this developing story can be found here.

Attorneys for the former Balch Springs police officer who killed 15-year-old Jordan Edwards have requested an emergency stay to delay the start of his murder trial.

The trial for 38-year-old Roy Oliver is scheduled to begin Thursday, but his defense lawyers filed the emergency request early Wednesday with the state's 5th District Court of Appeals.

By 5 p.m. Wednesday, the appellate court had not made a decision on the motion to stay the start of the trial. The court could release an opinion Thursday morning, when the trial is scheduled to begin.

Roy Oliver (Parker County Jail)

Defense attorneys allege that Oliver's rights were violated and the criminal indictments are invalid.

Oliver is charged with murder and four counts of aggravated assault by a public servant for shooting into a car full of teenagers, killing Jordan, in April 2017.

He says he shot into the car to protect his partner, who he believed was about to be hit by the vehicle.

Defense attorneys Jim Lane, Miles Brissette and Bob Gill filed a writ of habeas corpus last week to dismiss the criminal indictments.

They allege Oliver's constitutional rights were violated because prosecutors used statements he made to a Balch Springs internal affairs investigator as part of the case against him.

State District Judge Brandon Birmingham declined Tuesday to have a hearing on the writ, saying it doesn't fall within his court's jurisdiction.

The attorneys filed the emergency stay and a petition for a writ of mandamus with the state appellate court early Wednesday to ask that Birmingham have a hearing on the matter.

On Tuesday, Birmingham denied defense requests to recuse the Dallas County district attorney's office from the case and a motion for continuance to delay the trial. Birmingham has granted two continuances in the case, which was originally scheduled for trial in January.

"There's been a rush to trial on this case since the day these indictments were returned," Gill argued during one of the pre-trial hearings.

Gill said the judge should allow an hourlong hearing to address the "important constitutional question" of whether the criminal indictments are valid.

"The district attorney's office and the sheriff's department gained this information in an improper and unlawful manner," Gill argued.

Gill argued that the issue should be examined because Oliver was required to give a statement to an internal affairs investigator to try to keep his job, and such a statement should not be used by prosecutors.

Oliver was given what is known as a "Garrity warning," which states that what he tells an internal affairs investigator cannot be used against him in a criminal case.

Jordan Edwards was shot and killed as he left a house party in April of last year.

The Dallas County DA's office said only one person at the office has seen Oliver's statement. That person sealed it so that the prosecutors can't read it.

But defense counsel said criminal investigators and two Dallas County prosecutors were present while Oliver walked through the scene with internal affairs in the early hours after the fatal shooting. Information from that walk-through appears in the criminal case report, the defense attorneys say in their request to the appellate court.

"This information could not have been made known to detectives from any other source than Mr. Oliver," defense attorneys wrote.