June 8 (UPI) — The owner of a Massachusetts pizza chain was found guilty of forcing six employees to meet excessive work demands and threatening them with violence and deportation.

A federal jury convicted Stash’s Pizza owner Stavros “Steve” Papantoniadis, 48, on three counts of forced labor and three counts of attempted forced labor, according to a notice Friday from the U.S. Attorney’s Office in Massachusetts.

The verdict comes after a lengthy investigation into Papantoniadis, who has been in custody since March 2023.

His sentencing hearing is set for Sept. 12. Each count carries up to 20 years in prison and up to five years ofd supervised release.

According to trial records, Papantoniadis thinly staffed his pizza restaurants and purposefully hired undocumented workers, forcing them to take up to 14-hour shifts for as many as seven days a week.

Papantoniadis would control his workers via threats of physical harm or deportation. He would monitor them via surveillance cameras, which he had access to from his cellphone, and would repeatedly insult and harass them, according to court documents.

“Stavros Papantoniadis instilled fear in his employees. He underpaid and threatened them, some with fear of arrest and many with physical abuse. Today, the jury saw the indignities his employees were subjected to and have found Papantoniadis guilty of forced labor violations,” Michael Krol, special agent in charge of Homeland Security Investigations in New England, said in a statement.

In once instance, Papantoniadis reportedly choked a victim when he learned he was planning to quit.

When another victim tried to drive away from one of the restaurants, Papantoniadis chased them down Route 1 in Norwood and pretended to call local police in an effort to compel the victim to return to work.

Stash’s Pizza is a local chain that includes restaurants in Dorchester and Roslindale and previously had locations in Norwood, Norwell, Randolph, Weymouth and Wareham.

Papantoniadis has come under fire for alleged worker abuse before.

The U.S. Department of Labor in 2017 sued him and co-owner Polyxeny “Paulina” Papantoniadis for allegedly failing to pay proper overtime to 120 employees, misrepresenting pay rates and falsifying time records between November 2013 and March 2016.

The owners were ordered in 2019 to pay more than $300,000 in back wages.

Since then, the Massachusetts Attorney General’s Office received three complaints against Stash’s Pizza alleging wage and hour violations.