If the officer submitted the DNA as if they were a customer of the site, I wonder how they complied with the company's sample collection process. You usually have to submit a generous amount of saliva or cheek swabs.
There are sites that don't require a sample, but instead you upload the raw data from a site where you did submit a sample. Gedmatch is one such site. One could construct a file in a compatible format containing DNA data obtained from your own laboratory, upload to gedmatch, and analyse matches. This is how "ancient DNA" samples are uploaded to gedmatch to see how you match against thousand year old human DNA samples.
Could they make a fake saliva sample that has the same consistency as real saliva and whatever other characteristics that the analysis equipment depends on, but contains no DNA (or take a real saliva sample from someone and strip out the DNA), and then but the DNA they want to test into this fake saliva and submit that?