BERLIN—German prosecutors said Tuesday they have indicted a businessman on suspicion of breaking arms control laws by helping Russia purchase sophisticated machinery that could be used to make chemical weapons. The man, identified only as Alexander S. because of privacy rules, was arrested by German customs officials in the eastern city of Leipzig last year. Federal prosecutors said the suspect has also been formally charged with breaking export rules for selling restricted goods to a company in Russia and acting on behalf of a Russian intelligence agency. Prosecutors allege that a Russian company the suspect had business relations with was a front controlled by the intelligence agency to cover up purchases by Russia’s military industry. The purchased goods had dual uses, meaning they could be used for civilian purposes or to develop atomic, biological or chemical weapons or missiles, prosecutors said. They allege that the suspect was aware he needed …