A new type of resonance ionization laser ion source (RILIS) is presently being developed and tested at the off-line mass separator at Mainz University for future use at on-line exotic rare isotopes production facilities. For highest isobaric selectivity, this RILIS approach decouples the evaporation and ionization process. A further advantage is the generation of full temporal control of the resulting high quality ion beam. These facts are realized by a combination of atomizer ion repeller ion cooler and trap, which is operated together with a state-of-the-art, all solid state laser system. The principle and performance of this laser ion source trap (LIST) system are discussed applying simulation studies for the repeller-trap combination and first measurements for characterization.