Derek was a male human in the 24th century who was a former freelance smuggler and weapons runner who had been persuaded to join the Maquis by Ro Laren before 2373. After joining the Maquis, Derek used his contacts to gain weapons for the Maquis and built up a significant stockpile on planet Galion.
In late 2373, Derek traveled with a group of Maquis representatives to the Cardassian space station Tral Kliban to attempt to negotiate with the Cardassian-Dominion alliance and convince them that they were neutral in their conflict with the Federation Alliance. Unfortunately, their pleas went unheard and they were ordered to evacuate the Maquis colony on Galion; the Cardassians granted them a small amount of time to evacuate before they took the planet.
Following his return to Galion, Derek informed Ro of the decision to evacuate and told her that she was to take command of the transport Orb of Peace and take as many people off planet as she could. Derek was to remain behind to remove all the stockpiles of weapons before the Dominion arrived. (TNG - The Dominion War novel: Behind Enemy Lines)