DuPont, ex-employee plead not guilty, denying negligence in deadly LaPorte plant disaster FacebookTwitterEmail 1of30 The DuPont company and a former employee pleaded not guilty in a chemical disaster that killed four workers. Robert Tisnado, 39, and Gilbert "Gibby" Tisnado, 48, who died in a hazardous chemical leak at a DuPont plant in La Porte last week Friday, Nov. 21, 2014, in Pasadena. ( Johnny Hanson / Houston Chronicle )Johnny Hanson, Staff / Houston ChronicleShow MoreShow Less 2of30 DuPont employees and brothers, Robert Tisnado, left, 39 and Gilbert "Gibby" Tisnado, right, 48, died in the DuPont La Porte chemical leak Saturday. (Family Photos) DuPont employees and brothers, Robert Tisnado, left, 39 and Gilbert "Gibby" Tisnado, right, 48, died in the DuPont La Porte chemical leak Saturday. (Family Photos) Show MoreShow Less