You aren't a member of government. It's actually illegal to arrest a member of Congress on their way to the congressional floor. Hypothetically, if they shoot

You aren't a member of government. It's actually illegal to arrest a member of Congress on their way to the congressional floor. Hypothetically, if they shoot someone dead on the steps, and then disarm themselves so they aren't a threat anymore, then the police must still allow them to go into Congress to finish their debate. Congress itself can self police, but it's immune to being controlled by the executive branch (i.e. the police). If you could just arrest Congressmen on their way to the chambers, then you would see in a close vote that some Congressmen will never make it to the chambers because the police "found" something on them (or a police dog smelled weed on them).