A senior investigative journalist, who extensively covered underworld and crime for over two decades, was shot dead in broad daylight on Saturday by four motorbike-borne persons who pumped at least four bullets into him from behind at close range in suburban Powai. Jyotirmoy Dey (56), Editor (Special Investigation) with an English tabloid Mid-Day, was riding his motorcycle when he was gunned down in a daring attack that shocked the media fraternity. Dey was shot dead by unidentified persons in Powai at 15.30 hours, Joint Police Commissioner (Law & Order) Rajnish Seth said.