The only way the police would be involved is if somebody used that information to steal from the customers. You appear to be the primary suspect.
Your employer can fire you for being careless with customers' financial information. Your employer can fire you for causing the police to investigate the place of business. As long as you don't have a contract of employment that restricts their ability to do so, as long as the termination does not involve unlawful discrimination (e.g., based on race, religion, gender, etc.) your employer can fire you without cause.
That's entirely up to your employer.Quoting ejohnson254

