An alert popped up on his computer claiming he was under investigation for trying to buy child pornography and directed him to call a certain telephone number, according to court documents. The man told authorities his call led him to multiple unidentified people, including a person purporting to work in the fraud unit at Citizens Bank, and then another who claimed to be with the US Treasury Department. They spun a tale about a compromised Social Security number and an investigation into money laundering, and convinced the man to hand over thousands of dollars to “government agents” to secure his funds, court documents said.

He was directed to withdraw about $30,000 in cash from his Citizens account and buy $130,000 in gold bars from a Rhode Island precious metals dealer, and turn everything over to a courier who came to his house, according to court documents. He was told not to tell anyone about what was going on.

By mid-September, the man realized he was being scammed and spoke to local police and a special agent with Homeland Security Investigations.

When the scammers demanded $160,000 in gold bars, the federal authorities came up with their own plan with the help of the man and a local gold dealer.

The scammer who claimed to be in Citizens fraud unit instructed the man to wire $160,000 from his account to the gold dealer and said he would direct a “government agent” to come to his house in Narragansett to pick up the gold bars, according to court documents.

Working with law enforcement, the man and the gold dealer pretended to go through with the deal on Wednesday, according to court documents. The owner of the gold shop created a fake receipt documenting the sale of $160,000 and handed the man a box. Law enforcement had created fake gold bars, which were silver bars painted gold. When the scammer from the “Citizens fraud unit” asked the man for proof of the transaction, he texted pictures of the fake receipt and the fake bars, according to court records.

The caller from the “Citizens fraud unit” said he would have a government agent come to collect the goods. A driver in a black Mercedes SUV with a New Jersey license plate soon arrived at the house in Narragansett. The man handed over the box with fake gold bars, and the man in the Mercedes drove away.

Law enforcement had the Mercedes pulled over in Westbrook, Conn., about 40 miles from the Rhode Island state line. The driver was identified as Jirui Liu, 22, from Ontario, Canada. The bag holding the box of fake gold bars was on the floor of the passenger seat, according to court documents.

Through a Mandarin interpreter, Liu told the special agent for Homeland Security Investigations that he’d been in the United States visiting friends and playing poker in Las Vegas and Los Angeles, and was in the area taking “some stuff” back to New York for a guy he knew from a game called “League of Legends,” according to an affidavit supporting a warrant for his arrest. Liu said he didn’t know what was in the box, but that he was supposed to deliver it to some park in New York, according to the affidavit.

Liu is being held without bail after an arraignment Thursday in US District Court in Providence on charges of money laundering, fraud, and two counts of conspiracy. It was not immediately known if he had a lawyer.

Amanda Milkovits can be reached at amanda.milkovits@globe.com. Follow her @AmandaMilkovits.