Attorneys Tuesday began their defense of master rigger William Rapetti, who was blamed for causing the crane’s collapse and faces seven counts of manslaughter. The prosecution rested its case against Rapetti on Monday.

One of the prosecution’s final witnesses was Frank Stokes, an engineer who observed a different test at Lehigh University’s ATLSS Engineering Research Center. Stokes testified that his tests proved that damaged and improperly fastened slings caused the collapse.

Refuting Stokes’ testimony for the defense was Leo Y. Lee, a Lehigh-educated independent engineer who conducted a reenactment of his own by rigging a replica crane in a vacant lot in Red Hook, Brooklyn.

The results of Lee’s simulation, the defense and witness said, disproved key points of the prosecution’s case against Rapetti, including the assertion that the crane collapsed after one sling “popped,” causing the other three to “fail” and the crane’s six-ton collar to freefall.

Lee countered that his test called for a worker to intentionally slice through one of the four slings with a utility knife, the other three slings withstood the load for over half an hour, causing the collar they were supporting only to drop eight inches.

Based on his own inspection of the damaged crane, Lee said that the collapse was caused by faulty tie-beams breaking on the 9th floor, rather than the 18th, the floor onto which the crane was fastened while it was being “jumped” or extended the day of the collapse.

Lee said the connection “was not fabricated as per the design, and it caused a tear,” where the beam was bolted.

The defense has repeatedly argued construction at the site was rushed to take advantage of the housing boom, in one instance causing the crane’s installation engineer Peter Stroh to “spot-weld” the tie-beams on location, rather than having them taken for precise measurements.

Rapetti’s attorney, Arthur Aidala, explained outside the courtroom that if the tie-beams broke from the fall of the collar, as the prosecution alleges, the beams would have a “guillotine style” cut.

But Lee said one of the recovered tie-beams was “twisted off,” showing evidence of poor installation.

While the prosecution maintained a sun-bleached and damaged Metro sling broke first, Lee opined that one of the other three Lift-All brand slings was the first to pop, which jibes with a testimony of a prior eyewitness who said he heard a “pop” from the opposite corner of the collar than the prosecution has suggested.

The defense was expected to rest its case on Wednesday afternoon, and Justice Roger Hayes will inspect the remnants of the fallen crane in a lot in Red Hook, Brooklyn on Thursday.

Adam Klasfeld