Final answer:
The Federal Bureau of Investigation (FBI) is the agency most likely to lead an investigation for a bank robbery where the suspects have fled across state lines, as it is responsible for federal offenses and has jurisdiction across the United States.
Step-by-step explanation:
If two individuals rob a bank and then flee across state lines, the agency most likely to lead the investigation is the Federal Bureau of Investigation (FBI). The FBI is the primary federal law enforcement agency responsible for investigating federal offenses, especially when a crime involves crossing state borders.
The jurisdiction of the FBI allows them to pursue criminals beyond the limits of individual states, ensuring that criminals cannot evade law enforcement simply by crossing state lines.
It is also important to note that bank robbery is considered a federal crime, and the FBI has special jurisdiction in matters involving federally insured financial institutions. Furthermore, the FBI may collaborate with local and state law enforcement agencies to apprehend the suspects and conduct a thorough investigation. This cooperative approach ensures that all relevant legal authorities contribute to solving the crime and bringing the perpetrators to justice.