Final answer:
Congressional committees collect evidence using their powers to conduct hearings, issue subpoenas, and hold individuals in contempt. Their oversight function is critical for accountability and informing legislative actions.
Step-by-step explanation:
Congressional committees have several powers that assist them in gathering evidence during an investigation. These include the power to conduct hearings, the ability to subpoena witnesses and documents, and the power to hold individuals in contempt for failing to comply. Committees play a vital role in the legislative process, closely examining governmental operations, identifying issues for legislative review, and recommending actions to their respective chambers. Committee hearings can sometimes become highly politicized events, particularly when significant or controversial matters are involved. The oversight power of Congress is essential in ensuring accountability within federal agencies and can often lead to the creation of new legislation or amendments to existing laws, reflecting the deep involvement of Congress in the shaping of public policy.