Two powerhouse lawyers squared off in court Wednesday over who should be held responsible for a building collapse that killed six people inside a downtown Philadelphia store.

Nineteen shoppers and workers were buried in rubble when a towering brick wall left unbraced during a demolition project crushed an adjacent Salvation Army thrift shop in June 2013. Some of the survivors were left permanently injured.

Two unqualified demolition contractors are serving long prison terms over the catastrophe. But building owner Richard Basciano, a New York speculator hoping to redevelop a block of seedy properties he had held for 20 years, was never charged. And his architect, Plato Marinakos, who hired the demolition contractor, testified under a grant of immunity.

The victims are now seeking damages from both men, along with the Salvation Army and others.

Legal lion Richard Sprague argued Wednesday that Basciano was not involved in the demolition plan. Sprague served on Congressional panels investigating the John F. Kennedy and Martin Luther King assassinations. Both he and his client are 91.

Personal injury lawyer Robert Mongeluzzi, who represents family members and survivors, reminded the jury that Basciano hired cut-rate workers when public safety was involved — but Sprague to defend his assets in court. Mongeluzzi has won nine-figure verdicts over deadly construction accidents, and millions more over a fatal duck boat crash in Philadelphia.

The people killed inside the thrift store included two young women dropping off donations, an immigrant grandmother shopping on the busy sale day to send clothes back home, and a store worker who often talked over coffee with heavy equipment operator Sean Benscop, one of the men convicted in his death.

Sprague, citing experts who testified during the four-month trial, said Benscop was either responsible for the collapse or "the straw that broke the camel's back." Benscop used an excavator on the site that morning despite rules that an unbraced wall must be taken down by hand.

Given that neither Benscop nor Campbell have any assets — both were scraping to get by — the victims are looking past them for a payout, Sprague said.

"No way do they want justice. They seek revenge. And revenge can blind you," he said.

Mongeluzzi argued that Campbell and Benscop were so clueless they didn't understand the danger or realize they were most at risk. He said the Salvation Army kept the store open despite warnings about the ongoing demolition. A lawyer for the Salvation Army emphasized the charity's good deeds and called its staff blameless.

Campbell — offered just $112,000 to demolish the four-story building on one of Philadelphia's busiest downtown streets — gutted the building from the inside, destabilizing it, rather than take it down floor by floor. He was sentenced to 15 to 30 years. Benschop, who was operating the machine despite taking Percocet and marijuana for medical problems, was sentenced to 7½ to 15 years in prison. Both were convicted of involuntary manslaughter and other crimes.

The deaths led the city to tighten its requirements for demolition permits. A city inspector killed himself days after the collapse, although there was no evidence of wrongdoing on his part.

The jury is expected to begin deliberations Monday.