An aviation engineer who uncovered an alleged plot to bring down a helicopter belonging to one of India's wealthiest tycoons has been found dead – adding another layer of intrigue to the already-gripping mystery.
Bharat Borge, who formerly served in the Indian army, was found dead alongside railway tracks in Mumbai. A post-mortem examination concluded that he gad died from multiple injuries after being struck by a train on Tuesday morning.
The 45-year-old engineer had apparently blown the whistle on a possible sabotage plot against the country's leading industrialist, Anil Ambani, at the weekend.
Mr Borge found mud and gravel during a routine inspection of the gearbox of a helicopter owned by the Mumbai-based billionaire. Officials from Mr Ambani's company said the discovery was evidence of an attempt by his industrial rivals to try and kill him.
Police had questioned Mr Borge and other employees of an engineering company contracted to work on the helicopter but detectives said there was no suspicion that he was responsible for the sabotage.
Yet reports said that when Mr Borge's body was found in the Vile Parle neighbourhood of Mumbai, a note was discovered in his pocket addressed to the detective leading the investigation.
In the message, handwritten in the Marathi language, Mr Borge claimed that he had been visited by officials from Mr Ambani's company, the Reliance Anil Dhirubhai Ambani Group,just days earlier.
"My parents have brought me up with the right values and I would never get involved in any wrong activity," he wrote. "After you questioned me and left, Reliance officials visited me. They asked me some questions but I didn't tell them anything. One of them took my number and said they would talk to me again the next day. I got scared that I would be used."
Witnesses said they saw Mr Borge walking along the railway tracks before stepping in front of a train. Police have told his family they believe he committed suicide. But the family say they think there is something "fishy" about his death and have demanded that an investigation be carried out by India's federal investigation unit, the Central Bureau of Intelligence (CBI).
"He seemed tense [that he had made the discovery]. He informed his senior officers about the items in the helicopter. Maybe his co-workers would have given him some tension," Mr Borge's brother, Sambhaji, told reporters. "There is something fishy. The [investigation] should be done in a proper manner and the CBI should be involved if needed."
Mr Borge's cousin, Sambhaji Botre, told the Press Trust of India: "He was in the army for 20 years and he was strong. He never got depressed. We don't believe it was suicide. [His] wife and two children are in a state of shock and cannot believe that Bharat has committed suicide."
Mr Ambani is one of India's wealthiest and best-known tycoons, famous as much for a long-running and bitter dispute with his even wealthier brother as he is for running a telecommunications and banking business empire that has earned him a personal fortune of $12bn (£8.1bn).
He is listed as India's third wealthiest man but his brother Mukesh, who at 51 is two years older, holds the No 1 slot. Last year, the two almost ended up in court as a simmering row threatened to boil over.
When Mr Borge discovered the pebbles and gravel in the Bell-412 helicopter last week, officials at Mr Ambani's company claimed that his rivals were trying to kill him, though they did not specify anyone in particular.
They said Mr Ambani had been due to fly in the helicopter the next day. Captain RN Joshi, a senior pilot at Reliance Transport and Travels, one of Mr Ambani's companies, wrote in a letter to police and the chief minister of the state: "Business rivals are attempting to take away the life of Anil Ambani and senior officials of Reliance. This is clearly an attempt to murder.
"[Had the helicopter taken off, the gravel] would have entered the gearbox, thereby leading to loss of power and a resultant crash."
As police continued the sabotage investigation, a source at the company played down the significance of a meeting between company officials and Mr Borge and questioned the authenticity of the letter reportedly found on Mr Borge's body.
The source said officials had spoken with Mr Borge on Monday during a "chance meeting" at the airport and that he had been introduced to them as "the gentleman who had spotted the problem".
"He was introduced in a very positive way," said the source.