Allen Koh is CEO of Cardinal Education. He's been at it 15 years, beginning when he was still a student at Stanford.
He says there are only a couple dozen people around the world who work with the wealthiest families. He's one of them and so is Rick Singer.
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Koh is an elite college consultant catering to wealthy families.
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He met Rick Singer six years ago when one of those families hired both men, a move he likens to someone having more than one doctor.
"He was confident about his ability to get kids in with certainty and, in my work, we don't deal in certainties. We deal in probabilities and we're excellent about increasing probabilities but we can never get it to 100 percent," said Koh.
When ABC7 News asked Koh if Singer was offering 100 percent, he responded, "He said it was a done deal and I didn't have to worry."
The shared client went on to USC. His parent is now charged criminally in connection with paying Singer as part of the alleged "Varsity Blues" college admissions scheme.
A couple of years after first meeting Singer, Koh reached out to him for advice with a difficult case.
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"Looking back, I think he was offering me the side door. I didn't understand his explanation of it. It just didn't make sense to me. He talked about donations to his nonprofit and that that nonprofit in turn would make some sort of donation. It seemed to me like a legitimate but misguided development play," said Koh.
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Koh says a "development play" is when a family donates significant funds to a school, in the realm of millions often over the course of 10 or even 20 years.
In this case, Koh says Singer was only asking for a $500,000 donation to his foundation.
"He simply said by donating to his foundation, they have a relationship with the athletic department and they could donate it in a way that would make a meaningful difference," explained Koh.
"I couldn't understand and so I walked and I told my client this is not for you," he continued.
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It was the last interaction Koh said he had with Singer until Singer was charged criminally and became a cooperating witness.
Koh has since texted Singer asking if he wants to transfer his remaining students to him.
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"His response was that, with enough time, this will blow over and things will be fine," said Koh.
Koh also learned at least one other family whose eldest child he had worked with had since hired Singer for subsequent children and is now also charged criminally.
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When ABC7 News asked Koh if at any point he thought he should go to the authorities, Koh responded, "Well no, because I didn't think anything illegal was happening. It was simply explained to me as a donation to the university. It was never a payment would be made to an individual who would pocket the money."
Koh says most college consultants are mentors and educators and he hopes this scandal won't taint their good work.
Of those two shared clients, Koh says he has emailed one family telling them that he was sorry they were involved and that he was thinking of them. He says he received a response thanking him for being a friend.
Koh also says he thinks some parents knew, some parents didn't know and that he thinks some parents knew, but did not want to know. Koh also says he believes some of the kids absolutely knew, unless they weren't submitting their own college applications, which he says is one of the rules of applying to colleges.
See more stories and videos related to Operation Varsity Blues.