The video of the chopper disappearing into the fog has gone viral on social media

Coonoor, Tamil Nadu: The mobile phone of the man, who had filmed the helicopter crash that killed Chief of Defence Staff General Bipin Rawat and 12 others, has been sent for forensic examination, the police said today.

Joe, a wedding photographer from Coimbatore, had gone to the Katteri area in Tamil Nadu's hilly Nilgiris district along with his friend and family on December 8.

Out of curiosity, he had recorded the video of the ill-fated helicopter on his mobile phone, apparently moments before it crashed.

The video of the chopper disappearing into the fog has since gone viral on social media.

The district police have collected Joe's mobile phone and sent it to a forensic lab in Coimbatore, as part of the investigation in the case.

A probe is underway to ascertain why the photographer and few others with him had gone to the dense forest region, which is a prohibited area due to the frequent movement of wild animals, they said.

Meanwhile, the police department has sought details relating to the weather and temperature in the region on the day of the crash from the Meteorological department in Chennai.

The police are questioning witnesses to gather clues about the crash, they said.

General Rawat, his wife and 11 others were killed when the Mi-17VH helicopter crashed in a wooded valley in Coonoor's Katteri-Nanjappanchathram on Wednesday.