What was going on in that water in the Ney Pond is still largely a mystery.
Parasites were found in the pond, but they're not likely to explain all the deformities because they usually produce multiple legs, and most deformities show up as missing legs.
Drain tiles leading into the pond from nearby farm fields could carry fertilizer and pesticides, but it's very difficult to isolate which chemical might be the culprit, because chemicals break down and form new compounds which are hard to reproduce in the lab.
These complications turned out to be all too common at the other deformed frog hot-spots around the world.
Helgen's quest was made more difficult because she felt she didn't have the support of her bosses at the MPCA. She said they resisted asking the legislature for money because they thought it might endanger funding for other projects.
"There's a way that the state agencies do their budgets," she said. "They do priority planning way ahead, and the frogs popped up after they had set their priorities."
The legislature did provide money for several years, and Helgen coordinated a loose group of researchers from many fields in various parts of the country. She concentrated on collecting samples at the many locations she learned about from concerned citizens.
"Every year we didn't know if we'd be allowed to go back and work on it further," she said. "So my feeling was we were just trying to document the sites that had deformed frogs so they'd be available to other researchers."
The deformities emerged after a period of sudden and dramatic declines in populations of amphibians all over the world. Estimates differ, but some scientists say as many as 120 species of amphibians may have become extinct in the 1980s, and perhaps one-third of amphibians are at risk of extinction today.