Mandate? No. Ability? Yes. BTW no one said congress should reinvestigate every case.
Who else has the power to check the president/DOJ if there is an allegation they are committing a corrupt action? You trust people in such power to basically say "I investigated my good friend and he didn't do anything wrong, trust me, no need to have someone else look at it."?
Did you make this same argument against congress looking into the Steele Dossier fiasco?
Where is the evidence that it was a fishing expedition?
We already covered this
Says the person who believes red flag laws will be justly applied and executed.
The Steele Dosiere was debunked by the Dossiers leading author: Steele himself. That was about the time of Trump's first inauguration. Yet, the FBI continued to use that misinformation to go after Trump and his administration for years, costing tax payers millions, and resulting in no charges for Trump or his people as related to the Russia-Collusion hoax. Comey tried to claim ignorance, and after he left the FBI, he told an interviewer that, had he known then what he knows now, he would have never gone after Trump. Now he's being arrested and charged.
Not a good example, since we knew the hoax was a hoax early on, but the crime of basing an investigation on it continued until the Mueller report ended it.
With Homan, the people investigating found no evidence. This time they have the good sense to not keep taking bites at the same apple.