At 1710 local time, the DA-40 the homebuilt Giles 202 collided on final approach to Runway 18 at Georgetown Municipal Airport (GTU). Both airplanes were substantially damaged with the DA-40 pilot sustaining minor injuries; The Giles 202 pilot was seriously injured. A witness located at the self-serve refueling area, reported seeing the DA-40 on final approach when he noticed the Giles 202 on a very high short left base, with a relatively high sink rate. The witness stated that the DA-40 was on final at an approximate altitude of 200 feet AGL, with the Giles 202 overtaking the DA-40 quickly. Subsequently, the Giles 202 collided with the DA-40 approximately 50 feet AGL. Another witness, taxiing for departure, reported he did not hear any radio transmissions on the Common Traffic Advisory Frequency (CTAF).