I really find it hard to believe that you have never heard of Mafia involvement in Cola mines of Bihar even though your dad worked in Coal India. However just because you did not hear of it does not mean it doesn't exist.

There is a while section about this on Wikipedia.

https://en.m.wikipedia.org/wiki/Mafia_Raj

And this : https://www.google.com/url?sa=t&source=web&rct=j&url=http://...

Also this : https://en.m.wikipedia.org/wiki/Suryadeo_Singh

There are also a bunch of Bollywood movies with Coal Mafia as a background. "Gunday", though not about coal Mafia, is pretty entertaining.