Police say a months-long labour trafficking investigation with links to three provinces has led to four arrests.

Ontario Provincial Police say officers carried out arrests in the Toronto area and Simcoe County last week in connection to an investigation launched in February into the suspected trafficking of Mexican labourers.

The four accused, between the ages of 27 and 72, face charges of human trafficking and receiving material benefits from trafficking.

Police say the alleged victims, three men between the ages of 27 and 42, were recruited online, promised work permits and good paying jobs in Canada.

They were allegedly housed in an accused person’s basement and in short-term rentals across Canada while they were expected to work at recycling facilities in Red Deer. Alta., Levis, Que., as well as North Bay and Sault Ste. Marie, Ont.

In a statement, Det. Insp. Jordan Whitesell says the investigation—supported by federal border agents, Ontario’s labour ministry and police from across the province—is a “stark reminder that human trafficking remains a largely clandestine and complex crime that easily goes unnoticed.”