After graduating school, Byrne joined the Royal British Air Force and served during World War II. After his service, he went to work on a tea plantation in northern India. In the 1940's he opened Nepal’s first tiger hunting concession.
Back in the 1950s, some other researchers advocated killing a Bigfoot. They suggested that the only way science would accept proof of its existence was to provide an body for autopsy and testing. Byrne opposed that, instead advocating electronic surveillance and taking photos and tissue samples.
He found his first Yeti footprint in Sikkim in 1948. Sikkim is a state in northeast India, bordered by Bhutan, Tibet and Nepal. Part of the Himalayas, the area has a dramatic landscape that includes India’s highest mountain. Almost 35% of the state is covered by the Khangchendzonga National Park which makes the area a prime contender for Sasquatch/Yeti research. He launched a three-year project to track it in 1957.
Peter designed and led the Nepal Himalaya project financed by Tom Slick in 1957 through 1959. Findings he was part of include two sets of Yeti footprints , the paradoxical Yeti scalp and the mysterious Yeti hand in a temple at the village of Pangboche. Supporters contend that the hand is from a Yeti, but a finger bone from the hand was tested and the DNA was shown to be human. Forensic analysts concluded that the hair from the finger contained an unknown DNA sequence, giving cryptozoologists reason to contend it was indeed a Yeti and that the beings are closely related to humans. In more modern times, Joshua Gates and Jeffrey Meldrum each investigated this evidence with Meldrum considering the footprint too accurate to be fake or man-made, while Gates discovered hair samples that contained an unknown DNA sequence.
Tom Slick first heard accounts of the possible existence of a "Yeti hand" during one of his first "Abominable Snowman" treks in 1957. The Slick expeditions were the first to bring photographs of the hand back to the West. Later, Slick sponsored more expeditions in the area and gathered more information on the "Pangboche hand." In 1959 Peter Byrne, a member of Slick's expedition that year, reportedly stole pieces of the artifact after the monks who owned it refused to allow its removal for study. He claimed he had replaced the stolen bone fragment with a human bone. He smuggled the bones into India where actor James Stewart is said to have smuggled them out of the country in his suitcase. In 1991 it was discovered that an American anthropologist by the name of George Agogino, had retained samples of the alleged Yeti hand. Dr. Agogino put a tissue sample from the bone fragment in an envelope in his desk. It remained there for more than thirty years.
The NBC program Unsolved Mysteries obtained samples and asked the University of California to analyze it. The results were inconclusive, but seemed to indicate that the tissue probably came from a human hand. After that show broadcast, originally run on February 12, 1992, the entire hand was stolen from the monastery. Agogino, before his death in 2000, transferred his files on the Pangboche Yeti hand to Loren Coleman. Replicas of both the missing hand and skill were created in 2010 and gifted to the Pangboche monks in 2011. Late in 2011 it was announced that a finger belonging to the hand contained human DNA, following tests carried out in Edinburgh.
Byrne also headed several projects in the Pacific Northwest, including one that incorporated high-tech search tools and an 800 number tip line. While Slick was the “leader” of the Canadian/North American search for Sasquatch and Bob Titmus was the “field leader”, the pull of Slick’s other obligations distracted him from the hunt. Slick needed someone he knew to be in charge, and again chose Peter Byrne. Upon hearing of the discovery of more big footprints in northern California in 1959, Slick asked Byrne and his brother, Bryan Byrne, to head up a “Pacific Northwest Bigfoot Expedition” in 1960. Initially, this hunt included Rene Dahinden, John Green and Bob Titmus but there were personality conflicts and they didn't like having an Irishman running the show. Reportedly, Dahinden left after a month-and-a-half, and Green and Titmus stayed only a little longer. After Slick’s death in 1962, the operations shut down in the Pacific Northwest.
Byrne returned to the Bigfoot hunt in 1971, with funding by Ohio millionaire Tom Page. He began working with Dennis Jensen, and Roger Patterson until Page parted ways with Byrne, Jensen, and Roger Patterson. Peter could not continue his efforts until the early-1970s, when the Boston Academy of Applied Sciences began bankrolling Byrne, who promoted a no-kill position. He had established a Bigfoot Information Center in Oregon which continued for 9 years, from 1970-1979.
In 1992, Byrne was again bankrolled by Robert Rines and formed the Bigfoot Research Project, based in the Hood River region of Oregon. This search was extensive and employed helicopters, infra-red sensors and 1-800-BIGFOOT phone number. The project lasted about 5 years, but did not produce much good evidence.
After this project, Byrne was commissioned to investigate sightings of a Bigfoot-type creature in southern Florida. That work was documented in a production called Shaawanoki, produced by Andreas Wallach and Ronnie Roseman. He later investigated the Skunk Ape in southern Florida. The skunk ape, also known as the swamp cabbage man, swamp ape, stink ape, Florida Bigfoot, Louisiana Bigfoot, myakka ape, swampsquatch, and myakka skunk ape, were particularly common in the 1960s and 1970s. The large, foul-smelling, hairy, ape-like creature, which ran upright on two legs was even reported in the suburbs of Dade County, Florida. Joe Nickell has written that some of the reports may represent sightings of the black bear (Ursus americanus) and it is likely that other sightings are hoaxes or misidentification of wildlife. The United States National Park Service considers the skunk ape to be a hoax. In response to thousands of sightings, the Florida State Legislature in April introduced a bill (H.B.1664) in 1977, to protect the man-ape which stated, “Any person taking, possessing, harming or molesting any anthropoid or humanoid animal which is native to Florida, popularly known as the Skunk Ape, or doing any act reasonably capable of harming or molesting such animals…” Unfortunately, the Bill did not pass.
In the 1999 documentary Sasquatch Odyssey, Peter Byrne tells of having used “three million dollars of other people’s money” to search for Yeti and Bigfoot during the course of his life.