Authorities Wednesday arrested the former head of a West German company at the center of a scandal involving a suspected chemical weapons plant in Libya, a prosecutor said. West German and U.S. authorities said the company, Imhausen-Chemie, was the key supplier of material for the Libyan plant. Libya said the plant was for making pharmaceuticals, but U.S. and West German officials say it was intended to manufacture chemical weapons. Juergen Hippen-stiel-Imhausen, who was chief of Imhausen-Chemie until March, was arrested in the city of Bochum, said prosecutor Holger Preisendanz, who is leading the probe.