This is a closeup of the duct tape which Smolarek did not find in the never-emptied bag she claimed she found it in. It looks like there is gauze on it, or cream, or something.
I don't know what that white stuff is. But I cannot brainstorm anything a person doing an armed robbery might get on there, while allegedly tying a person up while his neighbors listen.
Mulrenin was wearing dark socks, pants, and jacket, and a dress shirt. Maybe they compressed his wound with toilet paper, to drive to the hospital without ruining the 300.
On his tidy bathroom counter, there is a loose roll of toilet paper.