A radioisotope identification and localization device having at least one radiation detector with three dimensional event localization that utilizes a spatial correlation of projection vectors arising from Compton scattering of gamma ray emissions. Source identification and location is supplied by a reconstruction that searches for solutions with radioactive material of unknown type. Detection, identification and localization does not require full energy deposition. Identification and location of known or unknown radioactive material somewhere in a large active area of interrogation is achieved.