How does the government monitor and check for unemployment check fraud?

How does the government make sure you're not collecting an unemployment check from the government, and at the same time working on a job? I know they send out forms you have to fill out stating whether you're working or not, but obviously they would need another method to verify you're telling the truth.

Also they run the unemployment receiver's Social Security Number through Social Security So if you are working then Social Security payments are being made and that is how they discover double dipping these audits of state programs are randomly done by each agency.

When you are hired by an Employer, they have to send in a "New Hire Packet". this includes your social security number. They can track you from that