Recognizing the characteristic of a simple group of Lie type from its Probabilistic Zeta function

We find a method to recognize the characteristic of a simple group of Lie type G from its Dirichlet polynomial P G ( s ) . This is enough to complete the proof of the following statement: if G is a simple group, H is a finite group and P G ( s ) = P H ( s ) , then H / Frat ( H ) ≅ G .