I think it's the correct terminology here. The police believe and suspect, the court try and prove. Arrests are always made 'on suspicion of'.
In addition, an arrest does not guarantee that the person will even be charged.
The the judge, judges.
Well that's how it's 'supposed' to work.
Unless it's a criminal offense and the defendant invoked his right to being judged by a jury.
The jury determine if the defendant is guilty of charges or not, based on the evidence given during the trial. The judge still judges the admissibility of evidence, the conduct of the prosecution and defence, etc., and also determines the punishment or sentence, based on sentencing guidelines, if the jury find the defendant guilty of any charges.