Satish Kalia was the man who shot five bullets at Dey on Jun 11. Kalia, a professional killer hired by underworld don Chotta Rajan.
Despite of killing Dey, the gang of seven who were arrested by the police were unaware of who he was, said Roy quoting the men who disclosed the details.
After realising whom they killed the gang panicked, spread out and fled to different parts of the country to escape from the clutches of the police.
The job carried out by the gang was "a very professional job", said Roy. The assailants followed Dey for days together, merely on the basis of physical description given to them by the contractors and his motor cycle's registration number.
The six killers were on motorcycle, while the seventh assailant was in a van, said Roy.
Roy further said a Czech revolver was used by Kalia and he was given 25 "extremely deadly cartridges" to carry out the operation. The three accused were arrested from Rameswaram, Tamil Nadu, while others were arrested from various parts of the country including Mumbai.
Police also claimed to have found ten mobile phones and deadly weapons from the gang.
"It was a very coordinated and copy book operation. A job very, very well done, very professionally done," said Roy.
On Jun 11, Dey, a senior crime journalist with the Mumbai-based tabloid Mid Day, was shot dead by a group of unidentified men outside a shopping mall in Powai on June 11.
Mumbai police probed at both personal and professional enmity as the motive behind the killing. Several angles including the involvement of the oil mafia and even cops that J Dey had written about in his new reports, were investigated into. An Assistant Commissioner of Police was also questioned in the case.