This came in today from a Marshall family member:

To quote the official police report, that was prepared by Wade Whitney, "I did not complete a Gun Shot Residue (GSR) kit on Marshall's hands because his hands had smeared blood on them. The smeared blood on his right hand was mainly on his right index finger which would be the area where Gun Shot Residue was most likely to be. I am aware based on my training and experience in similar cases that the Department of Justice can not test for Gun Shot Residue when the subject's hands are covered in blood because the blood washes away or obscures Gun Shot Residue and also interferes with the testing instrument. I am also aware that the Gun Shot Residue test conducted by the Department of Justice only determines whether or not a person was in an environment in which Gun Shot Residue was present and not whether the person fired a gun or not."

So they never completed a gunshot residue test and quickly cremated the body.