According to the NY Daily News, Shakeem Parker, 27, of W. 149th St, was charged with murder and criminal possession of a weapon in connection with the murder of former Harlem kingpin-turned-informant Alberto "Alpo" Martinez (pictured above) on October 31. 

Parker was already in custody at Rikers Island for a separate gun case, and detectives reportedly gathered information that supported Parker as the shooter. No further information regarding Parker's arrest, including a mugshot, has been released to the public. 

Source: NY Daily News