Garrow was born on March 4, 1936, the son of French-Canadian parents near the village of Dannemora in upstate New York. Robert Garrow had five brothers and sisters; one brother died at a very early age. Another brother, the oldest, was given away at birth and his whereabouts have never been ascertained.
The senior Robert Garrow was a mineworker and a heavy drinker who took out his frustrations and anger on his son. But his mother, the 5-foot-1, 270-pound Margaret Garrow, was well known in Mineville and her hostile, callous disposition weighed heavily on Robert's stunted development. "My mother was an extremely cruel person," one of her daughters said later. She was a violent, unforgiving woman who beat her children and displayed little compassion or understanding for any of them. "I more or less block everything out of the past," said her daughter Agnes years later, "I more or less closed it out of my mind, anything as a child."
Margaret beat Robert often and sometimes used whatever was handy at the time, including a crowbar, a belt or even a brick. On more than one occasion, she had assaulted the boy to a point where he was rendered unconscious. "My mother hit my brother Robert extremely hard with a piece of stove wood... I thought he was dead and I threw some water on him," said his sister Florence in 1974. "My mother used to whip him all the time."
With no formal education and no friends, Robert was left to fend for himself. He had no peer companionship and no meaningful adult supervision. At the age of 7, he worked on neighbor's farms for which his mother collected his pay. "My father gave him away to a farmer down in Moriah and he worked there on the farm until he was approximately 15 years old," his sister Florence said later to the court. Throughout the early years of his development, whenever he was at home, Robert endured frequent beatings from both mother and father. He spent most of his days and nights tending to livestock and performing chores that needed to be done. And most times, Robert was alone. Perhaps because of this isolation, Robert began having sexual contact with the animals on the farm. He had intercourse with cows, horses, sheep and dogs. When he first began this practice he may have been as young as 10.
"When I was probably about 10, 11, 12 years old, because I had no friends and I never used to play...I didn't know no children or anything. Of course I had to fool around with calves, horses, cows, you know," Garrow said during court testimony. He continued these activities for years without being discovered. He may have experienced a sense of gratification with animals that he was unable to achieve with humans. "I never had dates. Never knew anybody," Garrow said later. "I kept doing it for 10 years or so...then after, on other farms I worked," he said later. "And I used to put the milking machine on myself...you know, masturbate myself with it." Garrow's bizarre habits continued for many years. At the age of 15, he was sent to a state reform school for punching his father in the face after a heated argument. When he was released from the school a year later, he joined the Air Force.
In the military, Garrow suffered severe and constant ridicule for bed-wetting, a life-long habit that he managed to keep a secret until then. He later got into trouble when he stole money from an Air Force sergeant. He received a court martial and was sentenced to six months in a military prison in Florida. Garrow escaped from custody but was apprehended several days later. He was sentenced to one year in another military stockade in Georgia. After completing the prison term, he was discharged from the service. He had spent nearly two years in the service, almost all of it in jail.
Garrow returned to the upstate New York area where he worked at several jobs, but was unable to maintain steady employment. In June 1957, he married a local girl, Edith, in the Adirondack town of Lowville, some 20 miles south of Watertown. It would be the first time in his life that he had sexual relations with a female. Within a few months, the couple moved to the city of Albany where he got a job in a fast food restaurant. Soon, Garrow was arrested for burglarizing the store. Then in 1961, when he was 25 years old, he was arrested for the rape of a teenage girl after he knocked out her boyfriend with the butt of a pellet gun. The police were able to locate Garrow, who immediately tried to avoid arrest. During a hot pursuit, police fired several shots at the suspect who was eventually captured. After a trial, in which he was sentenced to 10 to 20 years in prison, he was shipped out to Clinton state prison, better known as Dannemora, the dumping ground for New York's toughest inmates.
He spent almost eight years in prison. When he was released in 1968, Garrow maintained a quiet existence working in a bakery and trying to stay out of trouble. But in 1972, he was arrested again in Syracuse, New York, on charges of unlawful imprisonment and drug violations. Garrow had tied up two female college students but later they refused to press charges. Then in 1973 he was accused of the sexual assault on the two little girls in Geddes. After he was released on bail, Garrow disappeared and never showed for the scheduled court date. An arrest warrant was issued and on that day, Garrow officially became a fugitive.