"I have spoken to the Mumbai Police Commissioner, and and Joint Commissioner (Crime) who are visiting the scene of crime. I have given instructions that the culprits be arrested as soon as possible," Patil said.
"Nobody will be spared."
Dey, working as Editor (Special Investigation) with English daily Mid-Day was shot dead in suburban Powai this afternoon by four unidentified gunmen.
The motive behind the murder would be known only after a preliminary inquiry, he said.
The Home Minister said he knew J Dey as a good and senior crime reporter.
Meanwhile, Maharashtra BJP spokesperson, Madhav Bhandari, described the murder as "most shocking".
He said the incident showed that the state Home Department had lost control of the law and order situation.
Published 11 June 2011, 12:15 IST