Canadian cab driver Juan Antonio Garcia-Jimenez cried in federal court in Detroit Monday as he apologized for a scam to smuggle illegal immigrants into the United States through a railroad tunnel under the Detroit River.

The 53-year-old Canadian resident collected at least $8,680 from nine illegal immigrants he directed through a walkway along an underground train tunnel that stretches 1.6 miles between Ontario, Canada and Detroit, Fox 2 reports.

Prosecutors told the court Garcia-Jimenez dropped the immigrants off at the tunnel on the Canadian side and told them when to go through to avoid cargo trains, a trek that’s extremely risky because the walkway is only 17 inches wide and in disrepair.

“They just walked right through the tunnel, which is a very dangerous thing,” Kris Grogan, a spokesman for U.S. Customs and Border Protection, told The Detroit News. “There is zero room. If a train would have come through there they would have been killed.”

Border Patrol agents arrested nine people who emerged from the tunnel in Detroit over the last year, including four in the last month who told authorities they paid Garcia-Jimenez $1,500 each to get into the U.S.

The illegal immigrants were charged with illegal entry, sentenced and deported, the U.S. Attorney’s Office told the news site.

Court documents show five of the illegal immigrants were farm workers in Leamington, Ontario, and Garcia-Jimenez used text messages to coordinate their border-crossings, The Canadian Press reports.

Garcia-Jimenez, who is from Guatemala but lives in Windsor, was arrested by Border Patrol agents in August 2018 on multiple smuggling charges when he went to Detroit to celebrate his wedding anniversary, The Detroit News reports.

“Due to the clandestine nature of this criminal activity, there is no way to be certain how many times he has smuggled aliens into the United States in the past,” Assistant U.S. Attorney Susan Fairchild wrote in the court filing. “Countless aliens could have illegally entered the United States with his assistance.”

A weeping Garcia-Jimenez told U.S. District Judge Stephen Murphy III on Monday that “I am sorry for what I have done,” but Murphy sentenced him to 16 months in a U.S. prison nonetheless.

Murphy also imposed a fine of $8,680 – the same amount Garcia-Jimenez extracted through his scheme.

“Today’s sentencing is the direct result of a whole of government approach to border security,” U.S. Border Patrol Chief Patrol Agent Douglas Harrison said. “The teamwork demonstrated in this case should be commended for their actions to arrest and prosecute Garcia-Jimenez who disregarded the safety of six aliens for financial gain.”