Trooper Gary Parker was born in Tarrytown, New York before moving to Gloucester, Massachusetts as a child. As a boy, his family settled in Wolfeboro, New Hampshire, where he graduated from Kingswood Regional High School. He went on to graduate from Johnson State College in Vermont before working with the Wolfeboro Police Department. Trooper Parker ultimately settled in Wolfeboro with his wife and son, where he was an avid golfer and enjoyed skiing.

After serving with the Wolfeboro Police Department for six years Trooper Parker was hired by the New Hampshire State Police on September 12, 1986. He was assigned to the Troop B barracks in Milford and was eventually transferred to Troop E. Prior to being transferred to Troop E, Trooper Parker was also assigned to the DWI Unit in Concord.

November 29, 1989 was Trooper Parker's first day assigned to Troop E and he was called upon to assist Trooper Joseph Gearty. Trooper Gearty had made an arrest in Campton and had brought the subject to the Plymouth Police Department for processing. Trooper Parker assisted Trooper Gearty in transporting the prisoner from the Plymouth Police Department to the Grafton County Jail in Haverhill. As they traveled north along Route 25 near the Wentworth/Warren town line, a tractor trailer carrying a load of lumber was speeding south towards them. As the tractor trailer rounded the turn near the town line, the load shifted causing the bindings to break. The lumber crushed the cruiser that Trooper Parker and Trooper Gearty were in. Trooper Parker and the prisoner were killed instantly. Trooper Gearty was transported to Speare Memorial Hospital in Plymouth. He died as a result of his injuries on November 30, 1989. The driver of the tractor trailer was uninjured.

At the time of his death, Trooper Parker was a three year veteran of the New Hampshire State Police and was only 30 years old. He was survived by his wife, who was pregnant with their second child, and his 16 month old son.