Dorman, 33, of Mebane, is accused of killing 33-year-old Lakeia Boxley and carrying her remains around in a backpack.
But attorney Lawrence Campbell said Tuesday that Boxley's bones should not have been given to her family for cremation, they should have been retained for evidence at trial.
Prosecutors say a fragment of the woman's skull was kept, and that is enough. They also stand by testing they say positively identifies Boxley.
The judge will consider the defense claims before making a ruling.