...then you can face charges for messing with it. BS charges, but when does that ever stop them? Hindering prosecution as a felony has become their go-to weapon of late, since the MS legislature added it as an option.
You can try asking the cops if it's theirs, but i have no idea if they would even tell you. Now that you've posted about it on the internet, i wouldn't mess with it, as you've pissed away your ignorance argument. I would just take it to the police and (assuming the ex-husband doesn't own the car) demand an investigation.Probably nothing would come of it, but in cases like thisthings tend to keep happening, and the case builds over time.
The US SC did recently rule against warrantless GPS tracking, so if it's the police then they need a warrant. Maybe they would tell you there's no active warrant against your cousin, after which you can safely conclude it's not a police tracker.
Hiring a PI is another way to go, as they would actually attempt to track the owner while the police probably wouldn't, but that's a $ question.