Asserting that testimony about Michael Slager's Taser during his murder trial was wrong, his attorneys have asked for another independent examination of the stun gun.
Slager's retrial in the shooting of Walter Scott isn't scheduled until August, but his defense team is continuing to build its case, a filing on Wednesday indicated.
The first trial ended in December with a hung jury.
"Testimony regarding the use of a Taser was introduced by the state that Mr. Slager believes was inaccurate," lawyer Andy Savage said in the motion, adding that an analysis would scientifically confirm or deny the contention. "The sole purpose of this request is to further Mr. Slager's pursuit of the truth regarding the allegations."
The proceeding is still months away, providing Slager's civil rights trial in federal court goes on as planned May 1. In both cases, he faces up to life in prison if convicted of the most serious charge he faces.
Slager, now 35, pulled over Scott's car for a broken brake light on April 4, 2015. He gave chase when Scott ran and tried to use the Taser to subdue the 50-year-old, but it didn't work. The officer said Scott fought him and grabbed the device, prompting his gunfire in self-defense.
An eyewitness video showed Scott turning from the confrontation and running away as the device bounced on the ground. Slager testified that he didn't know that at the time. Five of the eight bullets that Slager fired hit Scott from behind.
Both the prosecution and the defense called their own Taser experts during the trial. The defense highlighted DNA from both Scott and Slager that was found on the weapon.
Savage said Thursday that state testimony indicated that Scott had been affected by the Taser during the confrontation, but that there was no evidence that the device had made the electrical connection required for such an effect.
"We think it is important enough to have the testing done at our expense," he said.
Under Savage's proposal for further testing, the Taser, its cartridges, probes and wires would be sent to a private laboratory in Arizona. The Taser now is in South Carolina authorities' custody.