An ISU alumnus who worked on the country’s largest, most systematic investigation of UFOs died Thursday after a struggle with cancer. He was 70.

Roy Craig, who received his doctorate in physical chemistry from Iowa State in 1952, was chief field investigator for The Colorado Project, the official government search for verifiable evidence for the existence of UFOs. He was highly skeptical of UFOs, but was fascinated by the false reports of their existence.

“He felt the entire aspect of UFOs were the most important social phenomena of the last half of the 20th century,” said Hal Mansfield, a friend of Craig. “They opened up the minds of people to life on other planets and changed their perspective of Earth as the center of the universe.”

Craig’s professional career spanned many different branches of science, including nuclear weapons research, but he gained his professional notoriety as the chief field investigator for The Colorado Project, according to an obituary written by Mansfield.

“He gained notoriety because he was on the wrong side of the fence with those who ardently believed in the existence of UFOs,” Mansfield said. “Dr. Craig’s conclusions about UFOs didn’t come down on the believers’ side of the issue.”

At the end of this project, Craig and the other investigators released the Condor Report, one of the most important documents in UFO history, according to the obituary. The report stated scientists had nothing to gain from taking UFOs seriously and that the entire subject was largely useless to science.

The report was a response to the thousands of UFO sightings received by the Air Force during the 1950s and 1960s, according to Craig’s book, “UFOs: An Insider’s View of the Official Quest for Evidence.” Public interest in UFOs surged by sensationalized press attention, which stated the government kept UFOs secret under the guises of weather balloons and swamp gas.

As part of The Colorado Project, Craig personally investigated numerous UFO incidents, one involving a bow hunter from California who claimed he narrowly escaped a killer robot from space, armed with nothing but his bow and arrows, Craig wrote in his book.

Craig confirmed most of these “sightings” were merely hoaxes.

“The blind desire to believe can and does lead a person into absolute absurdities,” Craig wrote. “These cases illustrate the responses of human minds which are governed by the desire to believe in the reality of flying saucers.”

While the report that Craig co-authored debunked mysteries about outer space, he wrote that UFOs did get people to think about the possibility of extraterrestrial life.

He also wasn’t a complete UFO skeptic.

In the last chapter of his book, Craig included revolutionary theories that defended the possibility of interstellar travel. He wrote a few years of scientific progress would prove aliens traveling to earth was possible — at least theoretically.

“Roy said most people’s disbelief of UFOs existence came from our limited knowledge of physics and cosmology,” Mansfield said.

During his career, he taught physics at the University of Colorado and helped set up the Four Corners Research Institute, which offered environmental and other scientific investigations. He spent his retirement years on a 160-acre ranch in Ignacio, Colorado, where he took care of a herd of 60 llamas.