Is There a Trail of Blood Drops?

There's a trail of blood drops leading from the stairs and outside. Sam doesn't appear to have any bleeding injuries? No, just some bruising. The only way that that trail is occurring is going to be from the offender. And could be from Marilyn and the transfer of a large quantity of blood onto the weapon or onto the offender's hands. But without seeing photos and having distances of this trail, it sounds like this trail is fairly extensive.