The authority of Congress to investigate is an implied constitutional power. As James Madison explained in The Federalist Papers, "In framing a government which is to be administered by men over men…, you must first enable the government to control the governed; and in the next place oblige it to control itself." Congress has exercised this investigative power since the earliest days of the republic.
Elected to a two-year term, each representative serves the people of a specific congressional district by introducing bills and serving on committees, among other duties.