Certainly a possibility. I won't be losing any sleep over it tho.
No GSR on the victims hands, Blood spatter fund on gun, but none on the victims hands
Doctor Cohle stated that "The first shot would would have rended her unconscious but that respiration may have continued for a bit". He had spatter on his shirt so may have thought she was still alive so shot her again.
The gun had safety mechanisms that prevented accidental firing and she couldn't have shot herself twice because the first incapacitated her.
Rod Englert testified that he observed a high-velocity mist pattern of blood spatter on the fitted sheet and pillows. He also observed a void in the pattern consistent with something having been present at the time the shots were fired to intercept the high velocity mist and prevent it from being deposited on the sheet.
He testified that the void was consistent with someone firing the fatal shots while standing behind Sandra. That person would have intercepted some of the high velocity blood spatter which would otherwise have landed on the sheets. He found evidence of blood spatter on both sides of the gun. He concluded that the absence of blood spatter on Sandra's hands indicated that she did not fire the gun.
Englert examined Petitioner's clothing for evidence of high-velocity blood mist. Using a magnifying glass and high-intensity lights, he located numerous spots on Petitioner's shirt that appeared to be blood. He testified these spots were consistent with high-velocity blood mist. He testified that these spots were inconsistent with coughed or expirated blood.
An expert in DNA analysis, Shawn Weiss, testified that three of the spots identified by Englert as high-velocity blood spatter matched Sandra's DNA on all eight genetic markers tested. He testified that the probability of randomly selecting an unrelated individual with a DNA statistic consistent with Sandra's on this stain is one in 16.6 million for the Caucasian population.
Lots of forensics there!
Point is, it's been claimed that no one would stage a two shot death as a suicide ...... well, they did and they also passed a polygraph - TWICE!