An old friend of John Crichton, DK has known John since high school. They graduated together and were interested in space travel, so it shouldn't come as much of a surprise that they both entered work for IASA.
The two of them came up with a theory for reaching great speeds in space, by using a planet's gravity to increase speed in a slingshot effect. IASA approved this, and the Farscape project was born. In this, DK was to be with ground control while Crichton put their theory to the test piloting the Farscape 1 module. However, this didn't really go according to plan.
But when John managed to return to 2003 Earth in season 4, he came across DK again, a highly-regarded scientist and happily married. However, that didn't last long, as John's fears for Earth came true and a creature followed him back through the wormhole, killing DK and his wife.