In 2372, Mortonn entered into an arrangement with Tal Shiar operative Vrian, who needed slave labor for his covert operations in the DMZ. Over the next seven years, Mortonn would set up over a thousand refugees to be kidnapped by the Tal Shiar, and provide disinformation to the Maquis to cover up Vrian's activities.
After the Klingon attack on Cervalis V, Mortonn was contacted by Maquis leader Ben Bartholomew for help. He told Bartholomew that he had arranged for a Yridian freighter to pick up the Maquis survivors, but when Bartholomew and his companions arrived at the rendezvous coordinates, they found that Mortonn had betrayed them to the Romulans.
When the USS Pendragon began investigating the disappearance of the SS Artemis in 2379, Mortonn arranged for the abduction of Captain Sinclair and Ensign Jason Bartholomew. After the officer's escape, and subsequent exposure of Vrian's operation, Mortonn went into hiding for a brief period. (Star Trek: Pendragon: "L'Morte d'Maquis")