A law enforcement source said Benschop had used the excavator to remove a second-story beam just seconds before the building toppled onto the shop.
Benschop had begun work at the Market Street site about two weeks ago, according to law-enforcement sources. A routine blood test was conducted and results are pending, one law enforcement source said.
Reached by phone, Benschop said that he had operated his own demolition company for more than a year and that "Griff" hired him and his apparatus for the Market Street job.
That was an apparent reference to Griffin T. Campbell, the contractor hired by the property owner, Richard Basciano, to demolish the building. Campbell, who filed for bankruptcy protection in March, also has a criminal record stemming from a phony car-wreck scheme involving a Philadelphia police officer, according to court records.
Benschop declined to elaborate.
"There is nothing I can say right now," he said Thursday night. "There is an investigation."
Efforts to reach Campbell were unsuccessful Thursday. A young woman who came to the door at his residence in North Philadelphia said he was not there.
"He's distraught, that's all I can say," she said.
Benschop's most recent offense took place in January 2012, when police arrested him at his residence after responding to a late night radio call of a "person screaming."
During an argument with his 14-year-old son, Benschop allegedly punched the teenager, knocked him to the floor, and began choking him, according to court records. The charges were eventually dismissed in court.
Benschop served two prison terms in the 1990s for drug convictions, records show. It is unclear from the records how long he spent in jail.
In 2001, Benschop was charged with criminal mischief and carrying an illegal firearm after a neighbor told police of hearing him fire a gun in the back of the apartment house where he had been living.
Police arrested Benschop after recovering a .40-caliber shell casing in Benschop's yard. Those charges were also dismissed in court.
All 10 arrests were listed under the name Kary Roberts.
Contact Mike Newall at 215-854-2759 or firstname.lastname@example.org.
Inquirer staff writer Craig R. McCoy contributed to this article.