This case is crazy! I bet whoever was in charge of organizing evidence in that freezer got a reaming.
I can see how it would happen, though. I was briefly working at the local OCME here (covers half the province) and all of our unidentified skeletal remains are put in plastic bags, printed label on the bag, put in a small cardboard box which is taped shut, the ID code is written directly on the box, and the boxes are stacked on a shelf. It's not the most fool-proof method, I can see how tape and labels might get old, fall off, boxes are dropped, bags fall out, etc.