What to know about William 'Rick' Singer, the lynchpin of the college scam case who claimed to help nearly 800 families

The man at the center of the alleged $25 million college admissions cheating scandal seemed like a nice guy to some of his neighbors. But they say one recent move seemed unusual for him.

William "Rick" Singer put his multi-million dollar home, where he had lived for years and where he ran his business, up for sale last month.

"It was just kind of sudden and abrupt," neighbor Carn Darrow told ABC station KABC.

"I said, 'I saw you put your house up for sale. We are sorry to see you going.' He did tell us because of taxes in the state of California and business," she said about her conversation with Singer.

Singer, 58, has pleaded guilty on charges of racketeering conspiracy, money laundering conspiracy, conspiracy to defraud the United States and obstruction of justice. He faces 10 to 20 years in prison.

Singer's home in Newport Beach, California, was listed for sale on Feb. 20, nearly three weeks before the scandal was made public by authorities on March 12.

The real estate listing for the five bedroom home describes it as being "located on one of the most sought after blocks in the desirable enclave of Newport Heights."

The listing on real estate site RedFin reports that the home was bought for $1.5 million in 2012 and is now on the market for $2. 6 million.

That amounts to a fraction of the money that Singer is accused of accepting from parents during his time running a criminal college admission scheme.

Singer allegedly handled bribes totaling $25 million from parents between 2011 and 2018 "to guarantee their children's admission to elite schools," said Andrew Lelling, the U.S. attorney for the District of Massachusetts who is involved in the investigation.

One of Singer's close friends, Ron McKenna, told ABC News that he was "dumbfounded" by the charges.

"Greed never entered my mind when I thought of him, it was all about giving, not getting for him," McKenna told ABC News.

Investigators allege that Singer had parents contribute to a charity that he ran and he would then, among other things, arrange to either have someone take their children's SATs or ACTs for them or have their children's exams corrected in order to get higher scores. Singer also reportedly had deals with certain college coaches, who would allocate spots for the students at the prestigious schools.

In addition to allegedly using the money towards bribing officials, two schools – DePaul University in Illinois and Chapman University in California -- have since come forward to acknowledge that while they are not tied to the misdeeds of the cheating scheme, they did accept donations from Key Worldwide Foundation, Singer's charity.

DePaul University released a statement saying they "among the many universities that received gifts from the foundation at the center of the admissions fraud case."

"We have confirmed receiving gifts totaling $150,000 from Key Worldwide Foundation, managed by William Singer, founder of the Edge College & Career Network and the father of a DePaul student who graduated in 2017," they said in their statement, noting that the contributions were made when Singer's son was a student at the school.

"To date, our review has not revealed any reason to believe these donations are connected to recent indictments," the statement reads.

Chapman University said in a statement that they are “currently cooperating with the Department of Justice in their investigation.”

“Chapman University like all great institutions routinely receives funds from foundations and any irregularities in the gifts from the Key Worldwide Foundation, should they exist, were and are totally unknown to us. We take this matter very seriously and intend to review this relationship in depth to assure ourselves that our principles have not in any way been compromised,” the school’s statement reads.

Rebekah Hendershot co-wrote a book about getting into college with Singer in 2014 and worked with him to help students prepare their college application essays. She told USA Today that she felt pressure from parents to write their children's essays but "I wouldn't do that."

A 2005 Sacramento Business Journal profile detailed how, at that time, Singer ran a company called The CollegeSource and charged between $1,500 to $2,500 to help coach high schoolers to get into college. At the time, the company served 724 students and generated more than $1 million in revenue in 2004, according to the article.

One parent quoted in the 2005 article who hired him for the counseling service said that he had "instant credibility."

"And he has credibility with the kids. They liked him and trusted him immediately, not because he is a pushover -- he takes them to task. I don't know how, but he gets buy-in from them," the parent said.

On Tuesday, Lelling described how parents agreed to pay Singer to help bolster their children's applications.

"Singer worked with the parents to fabricate impressive athletic profiles for their kids including fake athletic credentials or honors or fake participation in elite club teams. In many instances, Singer helped parents take staged photographs of their children engaged in particular sports," Lelling said.

Singer claimed he “successfully engaged in the same scheme with nearly 800 other families,” according to court documents.

Carn Darrow's husband, Brian Darrow, said that Singer would often come over to their backyard and "help the boys with basketball and always encourage them."

"He's a very generous guy, was very cordial, seemed very happy, athletic, seemed very successful," Brian Darrow told KABC. "We really liked him."

ABC News' Desiree Adib contributed to this report.