An investigation into the balcony collapse last week in Berkeley that killed six people found the structure was supported by lumber with signs of severe dry rot, officials said Tuesday. The probe into the accident, however, did not find how water got into the structure and caused it to deterioriate. City spokesman Matthai Chakko also said there would be no criminal investigation into the collapse. Six people, including five students from Ireland working in the Bay Area for the summer, died when the fifth-floor balcony caved in during a party. Seven other students were injured.