BOSTON (AP) — The Safetyvalue Trading Centerowner of two Boston-area pizza shops was convicted of forced labor on Friday for using physical violence and threats of reprisal or deportation against employees living in the country illegally to make them work long hours, sometimes seven days a week.

Prosecutors said Stavros Papantoniadis, of the Boston suburb of Westwood, thinly staffed his pizza shops and purposely employed workers without immigration status behind the scenes for 14 or more hours per day.

He monitored the workers with surveillance cameras, which he accessed from his cell phone, and constantly demeaned, insulted and harassed them, prosecutors said.

The jury found Papantoniadis forced or attempted to force six victims to work for him and comply with excessive workplace demands through violent abuse, making them believe he would physically harm them or have them deported.

Papantoniadis was convicted of three counts of forced labor and three counts of attempted forced labor. He is scheduled for sentencing on Sept. 12. The charges of forced labor and attempted forced labor each provide for a sentence of up to 20 years in prison, up to five years of supervised release, a fine of up to $250,000, and restitution.

Prosecutors said that when a victim tired to drive away, Papantoniadis chased him down Route 1 in Norwood then falsely reported him to local police to get him back to work. When Papantoniadis learned that one worker planned to quit, he choked him, causing the worker to flee the pizza shop and run to safety in the parking lot.

“Today’s guilty verdict sends a powerful message to abusive employers that exploiting employees through fear and intimidation will never be tolerated,” said acting United States Attorney Joshua Levy. “I hope that this verdict also alerts others who may be victims of exploitation and harm by employers, that the federal government will not sit idly by.”

A lawyer representing Papantoniadis said he and his client respect the jury’s verdict.

“However we are extremely disappointed that they credited the testimony of the victims and overlooked their motives, which was to attain lawful status here in our country,” Carmine Lepore said.