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.