An Author Needs to Know
About the Police and the Law
What makes a crime federal rather than state?
A federal crime is an offense that has been made illegal either by federal law or one that occurs on federal property. Mail fraud which crosses state lines or involves the United States Postal Service is a federal offense. Other federal crimes include aircraft hijacking, kidnapping, bank robbery, child pornography, tax evasion, counterfeiting, art theft from a museum, damaging or destroying public mailboxes, immigration offenses, and since 1965, assassinating the President or Vice President, although these were not made federal crimes until after President John F. Kennedy's assassination.
Prosecution guidelines are established by the United States Attorney in each federal judicial district and by laws that Congress has already established. So never place your characters in the wrong courthouse. Federal crimes are prosecuted by United States Attorneys as opposed to State Attorneys and are handled in federal court.
Numerous federal agencies have been granted powers to investigate federal offenses. Some examples would be the Bureau of Alcohol, Tobacco, Firearms, and Explosives, Drug Enforcement Administration, Federal Bureau of Investigation, US Immigration and Customs Enforcement, Internal Revenue Service and the Secret Service. The men and women who work for these agencies are agents; DEA agents or FBI agents for example. They are not police officers.
If a crime is committed that includes breaking a federal law and a state law,
the federal law trumps and that is where the jurisdiction of the case will lie. Convicted offenders will serve time in a federal prison as opposed to a state facility.