Army Private Patrick Kelly and garda recruit Gary Sheehan were just 12 feet apart when they died from bullet wounds on the forest floor as the search team closed in on the IRA gang which had abducted the supermarket executive outside his home in Dublin.
RTE documentary, The Case I Can't Forget, reveals how the Irish forces were taken unawares by the ruthless efficiency of the paramilitary operatives when they finally came upon their hideout in Derrada Wood in Leitrim on December 16, 1983 after three weeks of searching.
Those closest to the rescuers killed in the double capital murder - which remains unsolved - speak about the ill-preparedness of the gardai and the soldiers involved in the joint operation that rescued Mr Tidey alive in the woods from the highly trained terrorists.
"They were prepared to kill, we came up here prepared to search," said retired Sergeant Major PJ Higgins (below) of the Defence Forces,
"We were very naive, because we always felt we were safe. Foolishly. We felt that they wouldn't have killed a soldier."
He was part of the team which took part in the chaotic search in 1983 for the kidnapped Quinnsworth executive in dense woodland.
"The conditions were horrendous. It was in the middle of December. It was teeming rain, and we had no webcam. Once you went into the wood, you could see nothing after you were in there five feet.
"It just became one black haze because you were actually bent down on your knees at all times.
"This was our first time ever to be involved in a mission like this. Were we properly equipped? No. Were we properly trained for such a mission? No.
"There were people just walking across the field, with Uzis hanging out. We didn't know who was who. It was chronic. It was something that you wouldn't see in a cartoon film really."
The son of Army Private Kelly, who was a young boy when he was killed, would later be told of his final moments.
"My father and his army colleagues heard [Garda] Gary Sheehan say the words, 'there's a man here and he won't speak to us...'", said David Kelly on the RTE documentary.
"Garda Sheehan took bullets to his head, he received extensive head injuries and he died instantly. My father received multiple bullet wounds from his ankles all the way up to his head.
"I was later told that my father didn't die straight away, and his colleagues could actually hear him in pain as he basically slowly bled to death in the wood that day, which was very difficult to hear."
Former Sergeant Major Higgins reveals in The Case I Can't Forget that the soldier's last words to his comrade were 'please don't leave me, I'm not going to make it'.
"This guy was an absolute gentleman. He was everything that you would want your son or daughter to be. It was horrendous."
The shocking killings were a watershed moment for Irish armed services, resulting in the setting up of the emergency response units and armed response units.
The Case I Can't Forget is on RTE One on Monday at 9.35pm.