From the Starr Report:
"Photographs of the victim at the incident scene depict apparent blood stains on his face and the right shoulder of his dress shirt. The staining on the shirt covers the top of the shoulder from the neck to the top of the arm and consists of saturating stains typical of having been caused by a flow of blood onto or soaking into the fabric. The stains on his face take the form of two drain tracks and one larger contact stain. . . ."
Sounds to me like there was a whole lot of blood on his shirt.
No where near as much blood as you would expect with large caliber bullet wound to the head. Blood pattern is more consistent with a small caliber wound to the neck.