Speckin and David Townshend (who was consulted as a ballistics expert), conducted an experiment in which they shot an anesthetized, terminally ill sheep with the same type of gun and bullets that were involved in Mrs. Duyst's death. The experiment resulted in no high velocity impact blood spatter on the shooter's hands or clothing.
The void pattern could simply be because of the gun regardless of who is holding it.
Someone too depressed and vindictive against her husband to contemplate the consequences.
High velocity blood spatter was on the gun, so WOULD have been on the hands of the shooter, there was no GSR or blood spatter on the hands of Sandra. As previously stated, there was also a clear pattern of someone being in the way of the blood spatter formation on the sheet.