Trooper Joseph Gearty was born into a large Irish-Catholic family in Norwood, Massachusetts in 1961. In 1980 he graduated from Blue Hills Regional High School in Canton, Massachusetts and went on to serve with the United States Army for three years as a military police officer. Trooper Gearty joined the New Hampshire State Police on August 31, 1984. He was eventually assigned to Troop F and settled in Rumney with his wife and son. Trooper Gearty was a fan of Irish Folk music and was known to listen and memorize Irish folk tunes in his cruiser.

On November 29, 1989 Trooper Gearty had made an arrest in Campton and had brought the subject to the Plymouth Police Department for processing. Trooper Gary 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 Gearty was a five year veteran of the New Hampshire State Police and was only 28 years old. He was survived by his wife and their six month old son.