MEXICO CITY, Oct 14 (Reuters) - Mexico City officials on Thursday said they were opening criminal cases against people and companies involved in building a stretch of Metro rail that collapsed, killing 26 people, and urged the firms to quickly come to settlement deals. The accident occurred in May when an overpass and train carriage on Metro Line 12 plummeted onto a stream of cars in the southeast of the city. An independent auditor found that missing bolts and poor welding contributed to the crash, findings confirmed in a separate investigation by the Mexico City Attorney General"s Office. "This prosecutor"s office has the evidence to charge a number of people and companies who were in charge of ensuring there would never be cause for a collapse," Mexico City"s Attorney General, Ernestina Godoy, told a news conference. The suspected people will face charges of homicide, causing injuries and property damage, she added, without providing details. She urged companies to reach agreements with the city to avoid legal processes and help provide reparations to victims. "Some companies that participated in Line 12 showed from the very beginning their interest in participate in the mitigation and repair of effects from the collapse," Godoy said. Mexican billionaire Carlos Slim has said his construction firm, Grupo Carso, which helped build the section that collapsed, will repair the line at no cost to the government. Without naming Grupo Carso, Godoy said she hoped companies would contribute to a fund to support people injured in the accident and the families of victims.