Well, they need to charge him with something that they believe they can actually prove to the court. Furthermore, it is obviously in the interest of the prosecu

Well, they need to charge him with something that they believe they can actually prove to the court. Furthermore, it is obviously in the interest of the prosecution to charge him with everything that they think they can prove, because if they pick just one and fail to prove it to the court they lose. Suppose for example they think they can prove charges A,B and C, and say, each of them comes with a maximum penalty of 1 year. Even if they seek a conviction for 6 months they will put forth all three charges, after all it might turn out that the court finds him innocent of A, and if they didn't bring B,C the prosecution is screwed.