A second demolition worker is now charged with murder in the deaths of six people killed in a Philadelphia building collapse.

A judge upgraded charges against backhoe operator Sean Benschop to third-degree murder after a preliminary hearing Tuesday. The judge also upheld the same six murder charges previously lodged against demolition contractor Griffin Campbell.

The men's lawyers did not immediately return calls for comment. Benschop's lawyer has argued that his client took orders from Campbell.

Benschop and Campbell remain in prison, awaiting trial in the June deaths inside a Salvation Army thrift store.

Prosecutors say Benschop had drugs in his system as he used heavy equipment to knock down an adjacent building that fell on the store. Both men are also charged with six counts of involuntary manslaughter.