What should a victim know about criminal identity theft, where someone is arrested under your identity, and the best way to deal with it? I'm wondering if there is some standard way to find out, or if basically anyone who's ever had their identity stolen is now vulnerable to having someone just give the victim's name/identity the next time they get arrested. How likely is this to happen, given that someone is a victim of identity theft?
There are a couple of components to this, part legal and part financial, which is why this is such a contentious question to be asking on money.stackexchange.
First, the financial:
If you want to find out if someone has been mucking with your identity you can check your credit history with TransUnion and Equifax for free. Look them up, visit their websites, and you will find the forms necessary to mail to them to have them mail you a free credit report on yourself. You can request this as often as you want with no detrimental effect on your credit score. These are known as "soft hits" to your credit.
Both companies offer a fee-based credit history alert system that lets you know when new activity like new cards, new loans, etc. are added to your history. The pricing is fairly low for the peace-of-mind you get, and allows you a quick response to any threats to your credit. They contact you when any suspicious changes occur on your account.
Next, the legal:
If you want to find out if someone has been arrested under your identity you can visit your local police station and have them conduct a background check on you. There is a cost, but it's not prohibitive. If someone has been using your identity for illegal activities there may be a warrant out for their/your arrest and you may be arrested on the spot. Make sure you have the contact information for your lawyer when you do this.
If you find someone has been arrested under your name, clearing that can be difficult. If it's a location-based crime, gather evidence that you were not in the area at the time and speak to your lawyer.
I would like to stress that this part of the answer is not something you want to be doing without good legal advice. I am not a lawyer, seek legal counsel before proceeding if you suspect someone has been committing crimes in your name.