PHILADELPHIA (Reuters) - The city inspector who checked a Philadelphia building before it collapsed last week and killed six people has died of an apparent suicide, a spokesman for the mayor said on Thursday.

The inspector, Ronald Wagenhoffer, 52, died of a self-inflicted gunshot wound to the chest on Wednesday night, said Mark McDonald, spokesman for Mayor Michael Nutter.

A 16-veteran of the city's Department of Licenses and Inspection, Wagenhoffer was found dead inside his vehicle in a wooded section of Shawmont Avenue in the Roxborough neighborhood of Philadelphia, McDonald said.

Earlier this week, Philadelphia District Attorney Seth Williams announced plans to convene a grand jury to investigate the extent of responsibility for last week's building collapse, which killed six people and injured 13 others.

Sean Benschop, who was operating the crane when the Market Street building in Center City fell, is the sole person charged so far in the case. He is being held without bail on charges of involuntary manslaughter, recklessly endangering another person, causing a catastrophe and risking a catastrophe.

The scope of the grand jury may include a look at the role of city agencies and their policies, Williams said.

The four-story building was being demolished and collapsed onto a Salvation Army Thrift Store next door.

On February 25, Wagenhoffer inspected the building that later collapsed and found no problem, McDonald said.

After a citizen complaint, Wagenhoffer inspected a neighboring building on May 14 and again found no problem, McDonald said.

(Reporting by Dave Warner; Editing by Barbara Goldberg; Editing by Lisa Von Ahn)