Help!!! My Colleague Is Stealing Our Company's Money And Changing Records

On the 5th of July 2017, i resumed work at a prestige hotel in Ikeja through a man i met at a car wash while i was washing cars for stipend to earn a living. The day i met him, i just finished washing a car and i worked up to him and requested an audience, and then told him i was looking for a job because am a computer engineering graduate trying a make a living, and all this took place sometime around February. He agreed to help and I, without giving much though didn't bother him anymore cause i was already tired of telling people i needed a job when i already know jobs are hard to come by these days. But surprisingly he came looking for my with the MD of a hotel and (devil is a lie) i wasnt at the car wash that moment,i went to see someone. He waited and waited and at some point was angry,then he left only for me to return few minutes later to be told he came looking for me...i was mad
*******************fast forward to 2weeks back*************************
He called one early morning and asked to meet me at the car wash so i could go see the MD that morning and i did. She interviewed me for few minutes, collected my C.V and asked me when i would like to resume work.So eager i said the next day and she was fine with it.Ever since that day i never saw her again but i was going to work and enjoying it too
**************************4days later*******************************
While on my shift, i made some sales and then early that morning,on my off day( cus i sleep in the office and handover sales made earlier the next day to my colleague) between 2am and 3am, two guest worked in to book a room. I assigned rooms to them and they paid me cash. I then handed the money to my colleague that was on duty that morning and went home only to return the following and discover while going thru the records that she only recorded one out of the two rooms i sold for her that morning. I searched the whole books for that room but couldn't find a trace of it, then i knew something was up. I never confronted her about it but i just decided to watch if twas gonna happen again.
**************************4days later after that*******************************
A similar thing occurred and this time so obvious. Four friends came in early in the morning on my off day and one of them paid cash for two rooms which i allocated to them and again gave the money to the same colleague before leaving that morning.On returning on my shift, she wrote down the two rooms sha but wrote 1POS and 1CASH, which was a lie cause i was the one that collected cash from them and they never paid thru POS.
**************************back to present day*******************************
Have been thing of confronting her directly but i cant cause i noticed too that she isnt alone in it, the manager is in with her and they are kind of close(i noticed it on the first day of resumption)
I also thought of telling the man that made me get the job cause later i found out that the MD is his wife, which was a shocker to me cause till now i didn't submit an application letter or bring in any guarantor before i got the job.
I don't wanna betray his trust either cause this might be a test to me
PLease friends what do i do?
NB: AM SURE THIS ISN'T THE FIRST TIME ITS HAPPENING....SHE OR SHOULD I SAY THEY HAVE BEEN DOING IT BEFORE I CAME. I DON'T HAVE PROOF OF THAT BUT I GUESS SO CUS NOW THEY THINK AM DUMB SINCE I DIDN'T NOTICE THE FIRST FRAUD ,WHICH I DID BUT KEPT QUIET THAT'S WHY THEY COMMITTED ANOTHER.