First time poster, long time lurker... I work in law enforcement but in Europe. Hopefully I might contribute something anyway.
An evidence freezer is where evidence specimens are kept (ie rape kits, human remains, stained clothing, swabs etc). The specimens are marked with case numbers etc.
I think this is a case where human remains were found without any markings in an evidence freezer at a coroner´s office so it´s unknown to which case they belong. That´s probably why there is only a coroner contact. My guess, based on the Namus case file, is that it´s just a small number of bones.
I think there are a couple of such cases discussed here.