Morphing From Male To Female In A DNA Sample

This is a murder case with a DNA sample from the crime scene. Initial tests on Y-STR showed a partial match to a male accused. A subsequent test on “supposedly” the same sample showed a female AMEL result.


Can a DNA sample "morph" from male to female or is this evidence that the police altered the DNA sample and substituted a different sample on the first test? The first test is in question because the arresting detective took an extra DNA sample when the accused was arrested.

Is there a Forensic DNA book or paper which comments about this situation? I have DNA Forensic Typing by John M. Butler if that book can provide the information. If this morphing is possible, under what circumstances can it occur?