A Woodbridge man allegedly received a warning on his computer while viewing child pornography online. The message, Prince William County police said, was an “FBI Warning,” which supposedly told him to click and pay a fine or risk being investigated.

So Jay Matthew Riley, 21, went to Prince William’s Garfield District Station to ask whether he had any warrants on file for child pornography, police said. They said he brought his computer with him.

The warning was a scam, police said. But when authorities searched Riley’s computer and, after obtaining a search warrant, his Woodmark Drive home, police found “inappropriate messages and photos of underage girls,” according to a statement.

“The circumstances behind [the charges] are unusual,” said Officer Jonathan Perok, a department spokesman.

Riley has been charged with three counts of possession of child pornography, one count of using a communication device to solicit certain offenses involving children, and one count of indecent liberties with a minor.

Riley is being held without bond, and a court date has not been scheduled. It was unclear whether he had retained a lawyer.

The indecent liberties charge, Perok said, stems from Riley’s alleged communication with a 13-year-old from Minnesota, from whom, authorities said, he solicited inappropriate photos.

The FBI warning scam that allegedly appeared on Riley’s screen is not necessarily associated with pornography Web sites. Some believe the ruse, Perok said. “Some people decide to click on the fine and pay it,” he said.

The charge is the third online-related child pornography case filed in the county this month. Police said Nathan Allen Allison, 19, of the 8600 block of Newton Place in Manassas tried to solicit a 15-year-old girl online. And a 22-year-old victim told law enforcement that when she was 15 in 2006, a Lorton man solicited photos via a Web site, police said. Police charged Stephan Adam Murphy, 42, of the 5900 block of Fox Glove Court with indecent liberties and possession of child pornography.