U.S. Attorney Andrew Lelling said via a live news conference "there can be no separate college admission system for the wealthy and there will not be a separate criminal justice system either".
Prosecutors have so far named 33 parents, 13 coaches, and associates of Singer's business. Loughlin has been taken into custody and is expected to make her first court appearance in federal court Wednesday for a bond hearing in Los Angeles, California. In October 2018, Huffman was recorded by the Federal Bureau of Investigation discussing participating in the same scheme for her younger daughter; however, she did not ultimately pursue it. A confidential informant told investigators that he told Huffman he could arrange for a third party to correct her daughter's answers on the SAT after she took it.
Another parent charged in the scheme, Manuel Henriquez, resigned as chief executive officer of the finance company Hercules Capital, the company said early on Wednesday.
Huffman is best known for her role as Lynette Scavo on "Desperate Housewives".
Loughlin and her husband Mossimo Giannulli are accused of paying $500,000 in bribes and fabricating photos showing their daughter as a competitive crew rower, in order to get her admission to the University of Southern California (USC).
Both of their daughters, Olivia and Isabella, are now studying at the university.
The colleges themselves are not targets, the prosecutor said.
"The Department of Justice believes that Yale has been the victim of a crime perpetrated by a former coach who no longer works at the university", Yale's president said in a statement.
The coach, Rudolph Meredith, resigned in November after 24 years running the women's soccer team. The witness says that he explained to the couple how the scheme would work.
The Fuller House star is among dozens charged in an alleged college admissions cheating scam involving elite colleges and universities including Yale, Georgetown, the University of Southern California and Stanford.
Parents paid as little as $15,000 and as much as $6 million to benefit from Singer's operation.
Thousands of dollars was funneled through a fake charity that claims to educate disadvantaged students while it was really just helping rich kids.
Singer also helped parents stage photographs of their children playing sports or even Photoshopped children's faces on to images of athletes downloaded from the internet to exaggerate their athletic credentials.
None of the students were charged and most remain at the universities, he said.
They were among 50 people charged in the scheme.
The scam also allegedly faked athletic profiles - creating the perception that certain students were strong athletes - and bribed college coaches.