A Time Lord was sent to Marinus to investigate violent disturbances in the space-time continuum and died there.
The Sixth Doctor, Peri Brown and Frobisher followed a distress signal from that Time Lord's TARDIS. Before dying, he who muttered "Planet 14". Since he was in his final incarnation, regeneration caused his body to rapidly break down into its constituent molecules. (COMIC: The World Shapers)