CHEAT FRAUD

Abnormal Accuracy. ...
Rapid Improvement. ...
Unusual Behavior. ...
Similarity to Computer Play. ...
Inconsistent Performance. ...
Unrealistic Endgame Precision. ...
Avoiding Mistakes in Critical Moments. ...
Unusually High Rating in Performance 

Are some of the ways to identify Cheating 

How to know for sure someone is cheating!

https://www.youtube.com/watch?v=GX0fyt4Uopw Check this link for more info