If someone would have marked or cordoned off where John's body was found before he was sent to hospital, then gathered the blood, maybe even shovel/clear the snow in that area, the additional accumulation would/could be noticeable and possibly photos with ruler marks as it accumulated.The logical thought would be the taillight pieces were found in and under the snow bank. However! The CW has never indicated they were found in the snowbank AFAIK. Plus if I understand Kevin O'Hara, the snow banks were not plowed all the way to the curb so the snowbanks were still positioned in the street. But John was not found by the snowbank either since he was 8-10 feet approximately on the grass. So where were these pieces of taillight found?
If I understand, there was no tent/cover of a death scene nor security attending it that day and following days until the SP brought their crew along with tail light pieces. how does that happen?