If you found out your Leader or Immediate Supervisor was doing something against the law, like fraud, what would you do?

Give them the chance to go forward and admit to it first... if they choose not to,...
Bring it to those higher up to deal with the sit-rep ...

I would confront them first to let them make a move. It's just hard for me to tell on people lol

More than likely feed them rope until they hang themselves.

My E-8 wanted me to better an audiogram. The Col was a General selectee. If he failed he would have not made general. I just said I was going to write down the correct repsonse. The E-8 had me step aside and he completed the exam. He was a great NCO. I was unclear on politics at the time. But I would do the same today. Just the way, I was raised.

Whistleblowers are not protected as scripted under the law (10 U.S.C., Section 1034) and the Inspector General will compromise your Complaint to those of your supervisors whom your Complaint is about and they will single you out, reprise against you with their wrath and finally prepare you for the pastures. No one listens to whistleblowers. If, by chance, an Inquiry is mentioned, know that this Inquiry is a weapon to tame congressional probes and legal action. All I am saying is that if you tread down the route of blowing the whistle against your supervisors then, be prepared to hang in there for the long haul, till justice is served. Don't loose hope and you have no time to venture into depression, because the Courts follow a six-year rule that is not in the Constitution. I am not discouraging you or your efforts, I am only trying to help build up your resilience.

In 2013, the GAO released GAO 12-362. In this report it has been documented that Inspectors General have arbitrarily closed Whistleblower complaints without investigating them at all. During Congressional Hearings the Army IG responded that the OTIG was understaffed. I didn't know understaffing is an excuse to disadvantage complainants; this is news to me. All I am saying is be very careful and alert, if you become a whistleblower.

Report it and make a note of it. Silence is acceptance of the act. Sometimes you have to have the moral courage and integrity to fall upon one's sword so to speak.
I had a reputation for calling BS and running things up that were not on the level. Got too many butt chewings and a handful of "don't air our dirty laundry out of house" counseling statements from officers that didn't have the evidence or means to bring it to a field grade 15 or higher. In the end my retirement award was the acting battalion CO signing my clearing papers as quickly as he could to get me gone. My EOS award was "lost" multiple times and I never received one.

ONE THING THATI WAS CURIOUS ABOUT WAS WHY I NEVER GOT MY AIT TRAINING AFTER BASIC!
ABOUT TO BE DRAFTED IN EARLY DEC 1963,
I JOINED THE RESERVES,(842nd QMC,KCKS)
I WAS TOLD I WOULD RECEIVE TRAINING AT FT LEONARD WOOD MO.
AFTER BASIC WOULD GET MY JOB TRAINIG ALSO AT FT WOOD!
STARTED BASIC EARLY MARCH 1964,
AND IT WENT QUITE BADLY ACCT MY
KLUTZINESS WHEN IT CAME TO MARCHING AND DRILL!
MY LACK OF PHYSICAL PERFORMANCE WAS NO HELP EITHER AS I NEVER WENT FOR HIGH SCHOOL SPORTS AFTER FRESHMAN FOOTBALL!
TOWARD THE END OF BASIC I WAS IN FEAR OF FLUNKING BASIC AND WOULD BE HELD AND RECYCLED!
I WAS PASSED HOWEVER BUT WAS NOT ALLOWED TO BE PART OF BASIC GRAD EVENTS , BEING USED AS A BARRACKS GUARD!
WHEN WE WERE GIVEN OUR ORDERS FOR OUR JOBS TRAINING I WAS EXPECTING
TO ATTEND THE FT LEONARD WOOD
ENGINEERS EQUPMENT OPERATORS SCHOOL!
INSTEAD OF THIS TRAINING I WAS SENT TO FT SHERIDAN ILLINOIS.
I WAS EAGER TO GET THIS TRAINING AS I WAS WANTING TO TRY TO GET A JOB AT BELGER CARTAGE IN KS CITY AND FELT ICOULD AT LEAST GET IN THE DOOR!
ANOTHER GUY WITH ME IN BASIC AND THE 842nd WAS ALSO EXPECTING TO GET CRANE TRAINING AT FT WOOD.
HE WAS ALSO SENT TO FT SHERIDAN!
ARRIVING AT SHERIDAN WE WERE ASSIGNED TO POST ENGINEERS, AND ON OUR FIRST DUTY DAY WE SERVICED A CRANE DOING AN OIL AND FILTER CHANGE AND COMPLETE LUBRICATION.
THE NEXT DAY WE WERE BOTH GIVEN SMALL FARM TRACTORS WITH MOWERS AND WERE ASSIGNED TO MOW THE OFFICERS GOLF COURSE FOR THE REMAINDER OF OUR 6 MONTHS RESERVE TIME!
I WAS MAD AS HELL FOR NOT GETTING THE CRANE TRAINING AND THE OTHER GUY WAS ALSO MAD AS HE WORKED HIWAY CONSTRUCTION AND FELT THE CRANE TRAINING WOULD HELP HIS TRIP UP THE LADDER!
NEITHER OF US BITCHED ABOUT THIS AS WE FELT IT WOULD CAUSE US TO BE ACTIVE DUTY WELL BEYOND THE ORIGINAL 6 MONTHS!
I WAS NOT SURPRISED TO SEE THIS HAPPEN TO ME BECAUSE I THOUGHT THAT THIS WAS IN REPRISAL FOR MY POOR SHOWING IN BASIC!
THE OTHER GUY HOWEVER HAD NO ISSUES WITH THE SYSTEM AS I DID.
I HAVE OFTEN WONDERED IF THEY SCREWED US OUT OF OUR TRAINING AND USED US AS LAWN CARE GUYS TO AVOID HIRING 2 CIVIL SERVICE GUYS TO CARE FOR THE GOLF COURSE SO THAT MONETARY FUNDING COULD BE SPENT ELSE WHERE!
AFTER BACH HOME FROM MY 6 MONTHS,
I LUCKED INTO A 30 YEAR CARREER WITH THE AT&SF RR!!
I WEASLED OUT OF THE RESERVES OCT 1967,
2 WEEKS BEFORE THE VIETNAM TRIP IN MAY 1968 WAS ANNOUNCED FOR THE 842nd!!

Unfortunately we had to do this once for real. In the course of our duties, my unit found that a senior officer was arranging the sale of high-demand electronic components out of the Army PX warehouse to local national "businessmen". And he was making a lot of money, from what we could see. We coordinated with the local MP's and they turned it over to CID. This very capable officer ended up leaving the Army under unhappy circumstances. We also found a mid-level Army staff officer who was having a sexual affair with a local national. I managed to "communicate" to this gentleman in an informal way that he should watch what he was doing. He was shocked, to say the least, but stopped his misbehavior. He did not get a bad outcome, at least while I was knowledgeable. It's never any fun to learn that someone in a position of trust has done wrong.

I would turn them in no question. No I would not notify them before turning them in.

Turn them in.. Anything immoral, illegal or unconstitutional, I have NO problem turning those in and watching them get booted out.