He graduated from Needham High School in 1985 and signed up for the Marine Corps with close friend, Jay Steeves, under the buddy program.
It would be at Guantanamo Bay that he would become involved in an incident, known as a "code red", which would play a major role in his military career and later become the inspiration for the film A Few Good Men.
Here, he was a part of Rifle Security Company, Windward Side, 2nd Platoon along with twenty-nine other Marines, overseen by Squad leader Christopher Lee Valdez.
[4] While stationed at Guantanamo Bay, Private First Class (PFC) William Alvarado wrote letters to a Texas Congressman complaining of poor conditions and illegal activities on the base, including Marines firing shots across the fence line into Cuba.
Seven of the ten accepted the plea bargain, including platoon leader Christopher Lee Valdez, who was the only one of the seven to get his discharge upgraded to "honorable".
Among these seven, some were represented by Deborah Sorkin, a recent graduate of Boston University Law School, who had signed up for three years on the U.S. Navy Judge Advocate General's Corps.
Deborah, sister to writer Aaron Sorkin, informed her brother about the case, which became the basis for the play and later film by the same name, A Few Good Men.
[6] Cox, along with two other Marines, elected to stand trial, arguing that they had committed this act under an order from a commanding officer and that murder had never been the intention.
Cox felt that the movie distorted the circumstances surrounding his being convicted of simple assault, though he resumed his military career after his court-martial.
Five other Marines who had been involved in the incident (Kevin Palermo, Ronald Peterson Jr., Brett Bentley, Dennis Snyder and Christopher Lee Valdez) hired lawyer Gary Patterson and filed a lawsuit in Texas State Court against Castle Rock and other Hollywood companies linked to the film.
The home was in good condition, though Tinsley did report all of the interior doors were open, their pet rabbit was hopping around unrestrained and several glasses appeared to have fallen over.
When she approached his truck, she found his keys in the ignition, an un-cashed paycheck on the dashboard and Cox's 9 mm handgun in the glove compartment.
The following day, on January 6, when no one had seen Cox and he failed to return home, Tinsley filed a missing person's report with the Natick Police Department.
The site of Cox's murder was also located between two hunting ranges, which authorities believed indicated that the killer had planned the crime, knowing that gunshots in that area would not elicit alarm from locals.
Immediately, police were mystified, as Cox was found wearing: his military issued, camouflage field jacket, his Marine Corps Scout Sniper hoodie, jeans and white sneakers.
Initially, investigators believed Cox had known his killer and had gone along willingly, though they found it bizarre that he had worn sneakers to walk half a mile into a wooded area when eight inches (20 cm) of snow had fallen the previous day.
[8] Investigators believed that Cox had likely known his killer and had gone along willingly, though details about what he was wearing, the keys in the ignition of his truck and the location in which he was found raised questions about that.