German prosecutors said Monday they had arrested an engineer on suspicion that he helped Libya in its efforts to build a nuclear weapons program, eight months after the man was named by authorities in Malaysia as a key figure in a network that spread nuclear secrets around the world. The man was arrested Thursday in the central German state of Hesse, according to the German federal prosecutor’s office, which did not release his full name. Officials close to the investigation identified him as Urs Tinner, 39, a member of a Swiss engineering family that has drawn scrutiny from European authorities and nonproliferation experts for more than two decades. Full Story