Which organization investigated theft of mail and assaults on postal staff?

The United States Postal Service (USPS) has its own specialized law enforcement agency known as the United States Postal Inspection Service (USPIS). This agency is specifically tasked with investigating crimes related to the mail, which includes the theft of mail and assaults on postal staff. The primary mission of the Postal Inspection Service is to protect the integrity of the mail system and its employees, ensuring that the postal infrastructure remains safe and secure for both staff and customers. This encompasses a variety of criminal activities, including fraud, counterfeit, and violence against postal workers, making it the most appropriate organization for investigating these particular crimes.

In contrast, the Federal Bureau of Investigation (FBI) usually handles broader federal crimes and issues of national security, while the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) focuses on specific areas related to explosives and firearms. Similarly, the Drug Enforcement Administration (DEA) concentrates on drug-related offenses. These organizations, while essential for law enforcement, do not have the jurisdiction or specialization needed for cases directly related to mail theft or assaults against postal staff that the Postal Inspection Service addresses.