An Indian citizen, CEO of two U.S. staffing firms, was arrested upon his return to the U.S. and charged with engineering what federal authorities are calling a “multi-year visa-fraud scheme” centered on the controversial H-1B visa.

Pradyumna Kumar Samal, 49, had earlier this year “fled the United States” amid a federal investigation into employment practices at the two Washington State staffing firms he led, Divensi and Azimetry, according to the U.S. Department of Justice.

Samal could not be reached for comment.

Samal’s two companies were in the business of supplying tech workers, including software-development engineers, to large corporations, including Fortune 500 firms, the department said in a press release.

Staffing companies and outsourcing firms have become prime targets for critics of the H-1B, a visa intended for workers with specialized knowledge doing specialty work. While major Silicon Valley tech companies rely heavily on H-1B workers, and push for an increase to the annual 85,000 cap on new visas, opponents of the H-1B point to alleged abuses by staffing and outsourcing firms, UC San Francisco, Disney and San Jose tech giant Cisco.

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Samal is accused of submitting, and directing employees to submit, fake documents purporting to show corporate clients agreeing to use workers named in H-1B applications.

“The forged documents included forged letters and fraudulent statements of work, which appeared as if they had been signed by senior executives at the two clients,” the department alleged.

The submitted documents falsely attested that the H-1B visas were for “specialty occupations,” according to an allegation in court documents.

Once U.S. Citizenship and Immigration approved the applications, the workers in question were “benched” — kept unpaid pending possible placement in a client firm of one of Samal’s companies, the department alleged.

“Nearly 200 workers may have been brought in under the phony applications,” the department alleged.

“The employees were forced to pay Samal’s companies a partially-refundable ‘security deposit’ of as much as $5,000 for the visa filings, regardless of whether they were assigned to any projects that provided them with income.”

Law enforcement officers arrested Samal on Tuesday as he arrived at Sea-Tac International Airport near Seattle after an international flight, the department reported. The U.S. Attorney’s office on Wednesday asked that Samal be kept in detention as a flight risk, and a hearing was scheduled for early this week.

The U.S. State Department and Department of Homeland Security in 2015 started investigating the two firms run by Samal, according to court documents. Authorities allege he was committing visa fraud between 2012 and 2015, according to court records.

Samal is accused of engineering a type of visa fraud known as a “bench-and-switch” scheme, court documents said. In this type of visa scam by a staffing company, a firm secures visas through fake or doctored documents, and then offers up workers to clients who are not designated in application materials. Cutting the time between a client’s agreement to use a worker and the receipt of an H-1B visa for the worker provides a business advantage, federal authorities said in a court filing.

“Shortening or eliminating the lag time enables petitioning companies to place employees at end clients faster than their competitors are able to,” a State Department special agent said in the court filing.