A crime scene tech has collected fiber evidence from a murder scene. Fibers were found on the victim's shirt and pants and placed in a plastic evidence bag. He notices a sheet next to the victim. The tech grabs it and puts it in its own separate plastic bag. Fibers were also found on a windowsill near the body. The text carefully removes it with his fingers and places it in a regular envelope.
What mistakes, if any, did this crime scene tech make while collecting this evidence?