Equipment Operator to Be Charged in Pa. Collapse A heavy equipment operator with a lengthy rap sheet was high on marijuana when a downtown building collapsed onto a thrift store, killing six people, and he will be charged in their deaths, a top city official said as authorities moved swiftly to assign blame for the deadly construction mishap. Police are looking for Sean Benschop, 42, to charge him with six counts each of involuntary manslaughter, risking a catastrophe, reckless endangerment and other offenses, Deputy Mayor Everett Gillison told The Associated Press on Friday evening, little more than two days after the collapse on Philadelphia's busy Market Street. Authorities believe Benschop had been using an excavator Wednesday when the remains of the four-story building gave way and toppled onto an attached Salvation Army thrift store, killing two employees and four customers, and injuring 13 others. A toxicology report showed "evidence that he was high" on marijuana, Gillison said. That finding, combined with witness statements and evidence from the scene, led to the decision Friday to raid his North Philadelphia home and later seek an arrest warrant, he said. "The D.A. has approved it (his arrest), and my police officers are out looking for him as we speak," said Gillison, deputy mayor for public safety. Benschop did not return phone messages left at numbers listed in his name, though he told The Philadelphia Inquirer on Thursday that he couldn't comment because of the investigation. Benschop, who also goes by the name Kary Roberts, has been arrested at least 11 times since 1994 on charges ranging from drugs to theft to weapons possession, according to court records. He was twice sentenced to prison in the 1990s after being convicted on drug trafficking charges. Benschop's last arrest, for aggravated assault, came in January 2012, but the case was dismissed for lack of evidence. As the criminal investigation heated up, at least two survivors sued the demolition contractor and building owner, alleging gross recklessness at the job site. The city, meanwhile, promised to crack down on the demolition industry. "We can do much better," Mayor Michael Nutter told a news conference Friday. We will not accept the status quo in the face of this tragedy. Nutter's reform plan for construction sites includes the random drug testing of heavy equipment operators. "If that's a factor here, that certainly takes things in a very different direction," Nutter said hours before the charges against Benschop were confirmed. The mayor also pledged to adopt tougher background requirements for demolition contractors, including information about each worker's experience, and more frequent site inspections when demolitions are underway. His plan could run into resistance from builders who say they're already highly regulated. "I think that before we do anything, before we rush to any judgment about how to fix what happened, we have to have all the facts," said Steven Lakin, executive managing director of the General Building Contractors Association, a trade group representing Philadelphia-area contractors. Everybody wants to regulate demolition contractors, but I'm not so sure that's the answer.