The St Catherine South Police arrested a boy, aged 16, on Friday, soon after a man was shot dead in the suburb of Portmore.A firearm was also seized, the police said. The constabulary, in a news release yesterday, said that the suspect was held and the gun seized less than an hour after the murder of 43-year-old promoter, Rohan Martin, otherwise called ''Roger', at McPherson Drive, Old Braeton in Portmore.