The former nuclear physicist had spent the last 50 years researching, lecturing and writing about UFOs.
The original civilian investigator of the Roswell incident, Friedman's life-long interest in the UFO phenomenon would see him leave his job as a physicist to study the subject full time in 1970.
Over the decades he lectured at over 600 colleges and to more than 100 professional groups across 50 US states and in 19 foreign countries.
He published at least 80 UFO-related papers, wrote several books and featured on numerous television documentaries and radio programs as well as in countless interviews.
He even provided written testimony to congressional hearings and appeared twice at the UN.
Preferring the term "flying saucer" to "UFO", Friedman was able to apply his own background and expertise as a nuclear physicist to the subject and remained convinced throughout his life that mankind is being visited by an intelligent extraterrestrial civilization.
"There is no doubt in my mind, after 37 years of study and investigation that the evidence is overwhelming that planet Earth is being visited by intelligently controlled vehicles whose origin is extraterrestrial," he once said.
"There are no acceptable arguments against flying saucer reality, only people who either haven't studied the relevant data or have a strong will not to believe that Earth is at the bottom of the heap sociologically and technologically in our local galactic neighborhood."