Did we get the full story?
I see nothing wrong with the aggrieved woman's actions - except - that she was using Department facilities for personal use.
A couple observations:
1. As has been pointed out by "J," "Expired" reagents don't just immediately stop working on their date of expiry. "Expiration Date" is often just a means of rotating stock and keeping the freshest material available. Real world example: When I buy a bottle of water, it has a "Use by" date printed on it. What? Does that mean that the day after "Use by" the contents are no longer "water?"
2. I am going to guess that the former Mrs. Gordon regularly laundered her Lothario's clothing, including his "delicate unmentionables." She probably even purchased them for him. Unless Sir Shag-a-Lot kept his dainties in a locked drawer or secured in his private office away from the marital home, Mrs. Gordon had lawful access to the, uh, briefs in question.
3. "Where there's smoke, there's fire." I doubt Mrs. Gordon would've gone through the effort to collect and test evidence if she didn't have reasonably strong suspicions that her husband was playing around.
Having said the above, I repeat my opening comment that the now ex-Mrs. Gordon erred by using State Police facilities to perform work for personal benefit. As a "forensics expert," she knew better and should have hired a third-party to perform the tests.
There's more to this story, though. As reported the Detroit Free Press, "Chamberlain also conducted a paternity test for one of Gordon's friends and allowed Gordon unauthorized access to the lab while she conducted the test, according to court testimony." I'd say the lady showed a pattern of very poor judgment. [http://www.freep.com/apps/pbcs.dll/article?AID=/20070822/NEWS06/708220397/1008]
I wish Ms. Chamberlain much success, both in finding new employment and an honorable mate.
(Full Disclosure: I am a licensed private investigator in the US and regularly work on domestic cases.)