My first reaction is that I don't buy it. First, blood darkens pretty darn quick, so to get that shade of red the blood would have to be close to still-wet. I don't know any artists willing to risk their scanner glass with a smear of something as difficult to remove as blood. Granted, watercolor paper holds color really well, but, well, just seems suspicious to me.

Second, it must've been one hell of a smash 'cause that would've taken a lot of blood to actually spread with a brush and not have it all coagulate on the brush.