Fifteen Chinese citizens have been indicted by a federal grand jury in Pittsburgh in a test-taking scheme centered on student visas.

The indictment announced Thursday says some alleged conspirators scammed tests run by Educational Testing Service and the College Board — such as the Scholastic Aptitude Test, or SAT — under false pretenses.

The indictment clearly identifies six suspects as students who paid to have tests taken and five as test-takers, but isn't clear on the role of the others — including three whose names remain under seal.

The indictment says some students paid nearly $6,000 to have the tests taken in their name.

Investigators say that was done by forging passports with the students' personal information next to a picture of the conspirator paid to take the tests.