What happened to Capt. Narinder Sharma?

Twenty eight year old Captain Narinder Kumar Sharma was killed during an exercise in Rajouri sector, in June 1982. Till date we don’t know how and why did it happen. The story put forth by his unit 17 Jat was that he slipped from a mountain and fell into a deep gorge.
Why was he going alone when an officer is almost always accompanied by a Jawan when he is out on some duty?
There are so many unanswered questions.
My mother mourned him for 29 years till she passed away in 2011.
What happened to Narinder?
Anyone who knows anything about it, please do contact me.
I will be really grateful to understand what really happened.