A Hillsborough couple formally entered guilty pleas Wednesday for paying a college preparatory counselor $600,000 to guarantee their two daughters' enrollment into the University of Southern California, according to federal prosecutors.

Bruce Isackson, 62, and Davina Isackson, 55, entered their pleas to one count each of conspiracy to commit mail fraud and honest services mail fraud. Bruce Isackson also pleaded guilty to one count each of money laundering conspiracy and conspiracy to defraud the IRS, according to prosecutors.

The couple is among the 33 parents charged in the wide-ranging scheme led by William "Rick" Singer, a Newport Beach man who worked with test proctors and athletic coaches at some of the nation's top universities to provide fake SAT and ACT scores and false athlete profiles for the students. The parents collectively paid $25 million in bribes written off as charitable contributions funneled through Singer's purported nonprofit, the Key Worldwide Foundation, which allowed them to deduct the payments when filing their federal income taxes.

The couple first engaged in the scheme in September 2015, when they had Singer make a false profile of a recruited soccer player for their older daughter that was submitted to Laura Janke, a former USC assistant coach for the sport, according to court documents. Five months later, the USC women's soccer coach moved the application to the regular admissions process due to a "clerical error."

Former USC women's head soccer coach Ali Khosroshanin sent the application to the head women's soccer coach at the University of California, Los Angeles, where the girl was given provisional admission for fall 2016.

In 2017, the couple also worked with Singer to create a false ACT score and fake rowing recruit profile for their younger daughter's application to USC, where she was given conditional admission that October but was told to keep the news under wraps until March 2018.

In both cases, the couple paid for the services by transferring shares of the stock, including 2,150 shares of Facebook stock valued at $251,249, to the foundation, court documents show.

The Isacksons also sought Singer's help in securing their third child false college entrance exam scores for their college application, but a phone call between both parties was intercepted by a court-authorized wiretap.

They appeared before U.S. Magistrate Judge Patti Saris in federal court in Boston, Massachusetts, on Wednesday morning and were scheduled for sentencing on July 31. Bruce Isackson, who was president of commercial real estate firm WP Investments in Woodside, is being represented by Michael T. Packard and Davina Isackson is being represented by Peter E. Gelhaar.

The two charges of mail fraud and honest services mail fraud and conspiracy to commit money laundering each carry a sentence of up to 20 years in prison and three years of supervised release. The fraud charge also includes a $250,000 payment or twice the gross gain or loss, whichever is greater; the money-laundering charge includes a fine of $500,000 or twice the value of the property involved.

For the charge of conspiracy to defraud the IRS, Bruce Isackson also faces a sentence of five years in prison, three years of supervised release and a $250,000 fine.

The Isacksons are among the 10 parents charged in the scheme with ties to the Midpeninsula. In addition to the Isacksons, Menlo Park residents Marjorie Klapper, 50, and Peter Jan Sartorio, 53, have agreed to plead guilty in the scheme.

Dr. Gregory Colburn, 51, and Amy Colburn, 59, both of Palo Alto; Marci Palatella, 63, of Hillsborough' and former Palo Altan William McGlashan, 55, each entered not-guilty pleas last month. Manuel Henriquez and Elizabeth Henriquez, both of Atherton, have yet to enter pleas in the case.

Singer pleaded guilty to several charges including racketeering conspiracy and obstruction of justice in March when news of the scam surfaced. He is scheduled to be sentenced on June 12 when he faces up to 65 years in prison, three years of supervised release, a $1.25 million fine and $400 in mandatory special assessment fees.

Related content:

• Stanford student allegedly paid $6.5 million for admission

• Listen to the March 15 episode of "Behind the Headlines," where Palo Alto college adviser John Raftrey discusses the implications of the nationwide admissions bribery scandal, now available on our YouTube channel and podcast.