Where is the heel?
I don't buy the explanation that the foot was only partially wet and the perpetrator fitted the wet-dry boundary to the edge of the mat.
You've created a false dichotomy. The bathmat was thick and ridged. It's entirely possible that if the weight was on the other foot, Guede placed the front of his foot onto the edge of the bathmat, but the rest of his foot remained suspended in the air above the bathroom floor. I think that the whole of Guede's right foot was covered in dilute blood/water, but that the back half of his foot never made contact with anything. Thus, no evidence of imprint from the back of his foot either on the mat or on the floor.
I was referring to unavoidable bloody water drops in the bathroom.
No way you wash your pants with so much water that your foot produces such a print and there is no other bloody water on the floor.
This is the same false dichotomy. Your use of the word "unavoidable" is illogical and wrong. Let me tell you how it's entirely possible to produce the bathmat print yet leave no bloody water drops in the bathroom:
1) Place bathmat outside shower door, and place towel on bathmat or on sink.
2) Shower blood from trouser legs with shower head - producing a dilute blood/water pool in the bottom of the shower that pools in the shower pan.
3) Stop shower, and open the shower door.
4) Step right foot briefly out of shower to extend reach to retrieve towel, leaving partial print on bathmat
5) Having retrieved towel, place foot back inside shower, and towel off trouser legs (thus preventing any dripping from trouser legs).
6) Rinse shower down thoroughly, then rinse soles of feet before drying soles of feet with towel.
7) Step out of shower and leave bathroom.
And if you're thinking anything along the lines of: "Ah, but in this scenario there would have been blood dripping from the trouser leg when the foot was placed on the bathmat to retrieve the towel", I'd argue two things: firstly, I think that this action would have been very quick - just enough time to grab the towel from that bathmat or the sink area; and second, it's possible that Guede only got blood on his left trouser leg - therefore only his left trouser leg would have been wet, and in my scenario the left leg remains entirely within the shower cubicle while the towel is retrieved.