BOSTON -- A fast-moving college admissions scandal moved from bombshell indictments to guilty pleas in a matter of hours, yet the full fallout from the federal case against the rich and famous could take months or more to unfold.

Big names such as actresses Felicity Huffman and Lori Loughlin headline the list of some 50 people charged in documents released Tuesday that describe a scheme to cheat the admissions process at eight sought-after schools. The parents bribed college coaches and other insiders to get their children into selective schools, authorities said.

At the centre of the scheme was admissions consultant William "Rick" Singer, founder of the Edge College & Career Network of Newport Beach, California, authorities said. Singer pleaded guilty and his lawyer, Donald Heller, said his client intends to co-operate fully with prosecutors and is "remorseful and contrite and wants to move on with his life."

Prosecutors said that parents paid Singer big money from 2011 up until just last month to bribe coaches and administrators to falsely make their children look like star athletes to boost their chances of getting accepted. The consultant also hired ringers to take college entrance exams for students, and paid off insiders at testing centres to correct students' answers.

Some parents spent hundreds of thousands of dollars and some as much as $6.5 million to guarantee their children's admission, officials said.

"These parents are a catalogue of wealth and privilege," U.S. Attorney Andrew Lelling said.

At least nine athletic coaches and 33 parents were charged. Dozens, including Huffman, the Emmy-winning star of ABC's "Desperate Housewives," were arrested by midday Tuesday. Huffman posted a $250,000 bond after an appearance in federal court in Los Angeles. Her husband, actor William H. Macy, has not been charged, though an FBI agent stated in an affidavit that he was in the room when Huffman first heard the pitch from a scam insider.

It was unclear when the "Full House" star Loughlin would turn herself in. Loughlin's husband, fashion designer Mossimo Giannulli, was released in Los Angeles after posting a $1 million bond.

On Wednesday, a Silicon Valley hedge fund announced that it is replacing its head after he became ensnared in the scandal.

Manuel Henriquez, who was also the top executive investment giant PIMCO until 2016, will be replaced as CEO and chairman of Hercules Capital in Palo Alto, California. Henriquez was arrested in New York City on Tuesday and released on $500,000 bail. Shares of the hedge fund plunged 9 per cent.

Hercules said that Henriquez will still hold a seat on the board and will serve as an adviser.

The coaches worked at schools such as Yale, Stanford, Georgetown, Wake Forest, the University of Texas, the University of Southern California and the University of California at Los Angeles.

Stanford's sailing coach John Vandemoer pleaded guilty Tuesday in Boston. A former Yale soccer coach pleaded guilty before the documents went public and helped build the case against others.

No students were charged, with authorities saying that in many cases the teenagers were unaware of what was going on. Several of the colleges involved made no mention of taking any action against the students.

Several defendants, including Huffman, were charged with conspiracy to commit fraud, punishable by up to 20 years in prison.

"For every student admitted through fraud, an honest and genuinely talented student was rejected," Lelling said.

Lelling said the investigation is continuing and authorities believe other parents were involved. The IRS is also investigating, since some parents allegedly disguised the bribes as charitable donations.

The colleges themselves are not targets, the prosecutor said. A number of the institutions moved quickly to fire or suspend the coaches and distance their name from the scandal, portraying themselves as victims. Stanford fired the sailing coach, and USC dropped its water polo coach and an athletic administrator. UCLA suspended its soccer coach, and Wake Forest did the same with its volleyball coach.

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AP Entertainment Writer Andrew Dalton contributed from Los Angeles