Authorities this week raided four Los Angeles colleges accused in an alleged “pay-to-stay” student visa fraud ring.

Officials say that immigrants enrolled in fake schools and attended nonexistent classes to dupe feds into granting them student visas. The schools allegedly catered to 1,500 Chinese and Korean immigrants who paid $3,000 per year for tuition.

Three defendants allegedly earned $6 million per year from the schools. In return for their students' money, investigators say the defendants certified the paperwork needed to show that immigrants were attending school, even though they weren't.

During a surprise visit to one of the schools, officials encountered only one student of the 900 enrolled.

Investigators say 90 percent of the students don’t even live in Los Angeles.

The three defendants have pleaded not guilty in the alleged scam. They face up to 16 years in prison, if convicted.

Read more from the Los Angeles Times:

The three are accused of having been involved in the operations of schools that offered immigration paperwork to students for as much as $1,800 for six months, assuring them they did not need to attend classes. Among those listed as active students were people living in Las Vegas, Seattle, Dallas and Honolulu, according to an affidavit in the case.

Authorities paid routine, unannounced visits at the schools – Prodee University/Neo-America Language School; Walter Jay M.D. Institute, an Educational Center; the American College of Forensic Studies; and Likie Fashion and Technology College – and found that there were few, if any, classes in session. Some had only one to three students. An instructor told investigators that one of his classes, Introduction to Politics, regularly had zero students, according to the affidavit.

When officials asked for records for the students, Shim sent shoddy files that listed the same bank account number for multiple students and contained clear signs that they’d been doctored, according to the affidavit.

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