He stood close to 6 feet and 4 inches, and used to ride a black Bajaj Pulsar.
The gentle and soft-spoken giant would walk into the dingy by-lanes and hotels of Behrampada in Bandra (E) with ease, to keep his network of informers alive.
But never had J Dey, who had seen the underworld mafia and its kingpins from close quarters, and produced reports on them for over a decade, been threatened.
So, who could have killed the veteran journalist?
Maharashtra home minister RR Patil said on Saturday an organised crime syndicate was behind the killing, but the killers were yet to be identified.
Police sources said he had never reported of any possible attack on him from any quarters.
Police sources said, it is an unwritten rule amongst the underworld mafia not to harm female relatives of rivals, journalists or police officials.
"It is highly unlikely that they would break the rule, but one can never vouch," added the officer.
"Prima facie this seems to be an act of vengeance, which could have risen from a recent article of J Dey," the officer said.
Police are also probing the involvement of quarrying mafia in J Dey's murder.
Dey had in a recent article reported of explosives and detonators going missing following a police raid on the quarrying mafia at Silvassa, a Naxal hotbed 190 km from Mumbai.
Jitendra Maru, an RTI activist from Silvassa said, "J Dey had planned to write a follow-up article on the quarrying mafia. He had talked to me on Friday afternoon, and asked me to be extra vigilant as his first report had made the state government order an enquiry."
The other possibility that police officials are investigating is the involvement of oil and diesel mafia who were exposed by J Dey in a series of recent articles in MiD DAY.
"But there has been a flux in underworld mafia operating in Mumbai, and new alliances have been formed. The newly recruited gunrunners are ruthless, and one cannot rule out their possibility in his killing," said a senior police officer, requesting anonymity.