A project manager who oversaw a construction crew involved in a fatal scaffolding collapse in 2009 was convicted Friday in the deaths of four workers under his charge.

An Ontario Superior Court judge found Vadim Kazenelson guilty of four counts of criminal negligence causing death and one count of criminal negligence causing bodily harm.

Kazenelson was aware that fall protections were not in place, but he nevertheless allowed his workers to board the swing stage, the judge said.

"In his failure to act, he showed wanton and reckless disregard," Judge Ian MacDonnell said.

Kazenelson sat quietly as his judgment was delivered. Family members of the victims gave each other sombre high-fives and pats on the back as they left the courtroom Friday.

The crew was 13 storeys up when the stage split in two on Christmas Eve in 2009. Kazenelson managed to hold onto a 13th-floor balcony but five men plummeted to the ground. Four died and one suffered serious injuries.

Another worker — the only one properly secured to a safety lifeline — was left suspended in mid-air.

Dilshod Marupov suffered serious injuries. Marupov told the court he had less than an hour of safety training.

Another worker, Shohruh Tojiddinov, testified Kazenelson didn't insist crew members be attached to lifelines.

He also said Kazenelson asked him to lie about the incident afterward.

Alesandrs Bondarevs, Aleksey Blumberg, Vladamir Korostin and site supervisor Fayzullo Fazilov fell 13 floors to their deaths. The men ranged from 25 to 40 years old and were from Latvia, Uzbekistan and Ukraine.

The construction company involved in the case, Metron Construction Corp., pleaded to criminal negligence causing death and was eventually fined $750,000 plus a victim surcharge — the first time in Ontario that the Criminal Code had been used to hold a company responsible for a worker's death.

The company that supplied the swing stage, Ottawa-based Swing N Scaff Inc., was fined $350,000 for failing to ensure the platform was in good condition.