In each case, the college hears from a lawyer, banker or other middleman. There's a large check or checks from a law firm. And instructions: The money should go for scholarships and the school should make no effort to track down the donor.
It's a mystery worthy of Sherlock Holmes or the cast of "CSI." An anonymous donor has so far given $76 million to 15 different colleges and universities and nobody -- at least publicly -- knows who's responsible.
The fund-raising world has been abuzz for weeks speculating on who the donor or donors might be. So far, there have been lots of clues, denials and no shortage of theories. But the source of the money has yet to surface.
Hunter College in New York City got $4 million for scholarships and $1 million to be used at president Jennifer Raab's discretion.
"We were very excited but we had to wonder if some things are too good to be true," Raab recalled of the two letters that arrived to her development office from a bank on behalf of the donor.
A quick call to the bank and the school confirmed the gift as a legitimate one but did not yield any clues about the donor's identity.
(Raab did ask the bank, located somewhere "in the western part of the country," to forward a thank you note to the donor.)
"It's an incredibly transformative gift for us," she said of the school that's one of the City University of New York's 20 colleges. "This is certainly the largest scholarship gift we've ever received."
Indeed, for most of the schools, this was the largest gift in their history.
Hunter serves an economically disadvantaged population. It has a significant population of black, Hispanic and southeast Asian students. Many are the first in their families to go to college. About 65 percent are women.
With an annual tuition of $4,600, the $4 million gift will go a long way.
"Hunter College is a place where the American dream can come true," Rabb said.
The 15 schools to receive the money to date are:
Michigan State University: $10 million
Purdue University: $8 million
University of Iowa: $7 million.
The University of Alaska-Anchorage: $7 million
Binghamton University: $6 million
University of Southern Mississippi: $6 million
The University of Maryland's University College: $6 million
The University of Colorado at Colorado Springs: $5.5 million
Hunter College: $5 million
Montclair State University: $5 million
Norfolk State University: $3.5 million
Pennsylvania State University-Harrisburg: $3 million
The University of North Carolina-Greensboro: $1.5 million.
University of North Carolina at Asheville: $1.5 million
Kalamazoo College: $1 million
Don't expect any more details about the donor from Hunter's Rabb or any of the other colleges. Even if they know more, they aren't sharing.
For instance, Purdue University refused to discuss the specifics about how the money was received to keep "with the spirit of the donor's wishes."
"We can best honor the donor by respecting his or her wishes and not speculating or discussing the details," spokeswoman Jeanne Norberg said.
So ABC News reached out to the experts, those who raise money for a living -- and even those who try to profile serial killers -- to find out how they would go about trying to solve this mystery.
Richard J. Gelles, the dean of the School of Social Policy & Practice at the University of Pennsylvania who is involved with the school's fund-raising efforts, said, "Donating is a certain part brain and a larger part heart," Gelles said. "People give because they have an emotional attachment. And that is almost always based on experience."
So like any good mystery, let's start with what we do know.
The 15 colleges all have female presidents. All but one -- Kalamazoo College -- are public institutions. And all were in the East Coast or Midwest until last week's gift in Alaska.
Gelles points out that there is more. A lot of colleges have female presidents, including the University of Pennsylvania, Princeton and Harvard.
"Maybe it's not just a woman president but something that the woman president said or did that made the donor feel, 'this is someone I can trust with my money,'" he said.
Maybe there is a common theme: some issue each president has mentioned in a speech. Maybe they were all in the same sorority.
Gelles sees a common trend in a person who wants the most bang for his or her buck, somebody who wants to really transform a university.
"It's always a great question: If you had a million dollars, do you give it to Harvard or the University of Massachusetts? One line of reasoning, especially in this economy, is that the University of Massachusetts needs it more. The other line of reasoning is: Harvard might do a better job with it," he said. "A million dollars isn't going to be transformative at Harvard. A million dollars is much more transformative at a public institution."
OK, so that's a start but many people would like to make a difference.
Moguls like Martha Stewart and former eBay president Meg Whitman have also come up as possible candidates.
But several experts suggest that the donor is an older person not used to being in the public spotlight.
Brad Garrett, a former FBI agent and ABC News consultant, said the key to profiling is to start with what you have, something that is tangible. He equated the donation mystery to a crime scene or searching for a missing person.
"Is there something unique about these universities where they have a particular type of program that's unique for women or they specialize in something?" Garrett said.
For all we know, maybe they all have a great art therapy program or shadow puppet class that appeals to the donor.
The largest donation to date, $10 million, went to Michigan State University. Purdue University got $8 million and the University of Iowa and the University of Alaska Anchorage each got $7 million. On the low end, Kalamazoo College received $1 million.
"Why did they get so much more than anybody else?" Garrett said of Michigan. "That tells me that, maybe, there is something unique or particular about that university."
Garrett would then analyze the donor lists at each school.
"I would see who has given money in the past because they may not have given money anonymously last year or two years ago," he said.
Maybe somebody has made gifts to several of these schools in the past. Maybe there is something about one of the past big donors that jumps out.
Garrett said something triggered this donor to make all these donations. Maybe a spouse died. Maybe they are dying or already died and requested their estate to make the gifts.
Whatever the answer, Garrett predicted it would take a long time to crack the code.
Like many others, Melissa Berman, who runs Rockefeller Philanthropy Advisers, a New York-based advisory service for donors, suggested that it was probably a female.
"I think the most obviously clue is that these are all institutions run by women," Berman said. "Most of them of are public institutions and that much of the money is designated for scholarships for low-income or disadvantaged students. So that tells me that this would be an individual who is or was very concerned about issues of access to opportunity."
That doesn't necessarily mean they are a self-made millionaire or somebody who comes from a poor background.
"It's also possible that it was somebody who had means but recognized how fortunate she was and how life-altering higher education is," Berman said.
Reading further into it, Berman suggested that the donor is an older woman who is not used to being in the public eye.
"It's the anonymity that's really so interesting and such an unusual feature," Berman said. "Most people wouldn't think that there's any problem with being identified as being a multi-million donor to a public institution for scholarship funds, especially people who are self-made and who are younger or middle-aged, including the baby-boomer generation."
It's the World War II generation, she said, who tends to shy away from publicity.
"An elderly women who inherited money either from a family or a spouse might not be as comfortable being in the spotlight if she wasn't in the spotlight a lot during her life," Berman said. "I think people who are self-made and successful are comfortable with attention."
So why all this secrecy?
"This person doesn't want to be turned into another Bill Gates and hear from everybody under the sun," the University of Pennsylvania's Gelles said. "The economy has really wreaked havoc with donations. If you're still in a position to make a donation, you're not exactly going to want to advertise it because hungry institutions having a difficult time meeting their budgets, who do worthy things, are going to descend on you if they think you have the capacity and might be even modestly related to their mission."
Anonymous donations are up in this down economy, according to the Chronicle of Philanthropy.
From June 2008 to April 2009, there were 80 anonymous gifts tracked by the publication of $1 million or more. That's nearly 19 percent of the 422 total during that period. In the past decade, the proportion of large gifts that were made anonymously has ranged from 3 to 5 percent.
"This is clearly somebody who wants to move a needle and is at a stage in life where it is important to do," Gelles said. "I'm thinking they are not young because young people generally don't know who they are yet and want more publicity."