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 PG(s). This is enough to complete the proof of the following statement: if G is a simple group, H is a finite group and PG(s)=PH(s), then H/Frat(H)≅G.