Two brothers were charged with a string of offences in connection with a large-scale counterfeit THC vaping operation.

Tyler Huffhines, 20, and his 23-year-old brother, Jacob Huffhines, of Paddock Lake in the US state of Wisconsin, face numerous charges including possession of THC with the intent to deliver, maintaining a drug trafficking place, identity theft, possession of a firearm by a felon and cocaine possession.

And officers are now investigating whether the operation – believed to be one of the largest of its kind in America – is tied to a spate of vaping-related deaths and illnesses across the US.

“Many of the people hurt very possibly are the cause of this family’s willingness to make money at other people’s expense,” Kenosha County Sheriff David Beth told the Journal Sentinel.

Officers released this image of the cartridges

The paper reports Tyler Huffhines told detectives he bought legal THC vape cartridges in California for $2.50 each and sold them for $15 in Wisconsin.

He eventually worked out he could boost profits by buying empty vape cartridges and jars of liquid THC and employed 10 people to fill them.

The cartridges contained as much as 1,000 mg of THC — more than 150 times what the label indicated, authorities said.

Huffhines paid his workers $20 an hour but switched to paying them 30 cents per cartridge to increase productivity.

“You invest more, you make more. No risk, no reward,” Tyler Huffhines told detectives, according to law enforcement documents.

His staff reportedly churned out 3,000 to 5,000 counterfeit vaping cartridges a day.

Cops were alerted when local parents caught their high school student son with THC vape cartridges.