One of his confidants was Ishara Yar, sister to Natasha Yar. In 2367 he offered to help the USS Enterprise-D rescue a Federation crew from a rival faction called the Alliance. Hayne sent Ishara to the Enterprise-D to help them. In reality, this was part of the plot to disable the Alliance's defensive grid, so that his soldiers could attack the rival faction.
Each side had an implanted proximity detector inserted in their chest that set off an alarm if they went into the others' territory. Hayne suggested that if someone on the Enterprise-D could remove Ishara's implant, she could lead them to the Federation crew. Once the implant was gone, Ishara could disable the defensive grid. Data and Commander Riker, after rescuing the crew, stopped Ishara as she was disabling the fusion generator. (TNG: "Legacy")