Can Congressmen be indicted and subpoenaed to appear before a Grand Jury?

I suspect they can. I can think of one Congressman at present that has gotten himself deeply involved in this Russian scandal. He could very possibly be tried for obstruction, by giving assistance to those trying to block a legal investigation of the United States of America?

There are so many issues that Mueller needs to address. But his main focus has to be the threat from the White House that he can, in fact, be fired. We wish that he could hurry thru this exercise for the citizens. But, as MLK, Jr once so eloquently stated, 'the arc of the moral universe is long, but it bends toward justice."