During the last stages of the Galactic Civil War, Fleet Admiral Gallius Rax installed inorganic bio-chips (also known as control chips) in the brain stems of a hundred Rebel Alliance prisoners at Ashmead's Lock prison on the planet Kashyyyk. These prisoners were part of a secret contingency plan to assassinate New Republic government officials and military commanders during the Liberation Day celebrations on Chandrila in 5 ABY. Rax and his undercover agent Windom Traducier used a transponder installed at the Hanna City opera house to transmit signals which activated the agents.
Prisoners installed with the bio-chips included Brentin Lore Wexley, Jonda Jae-Talwar, and Esdo. The unwilling assassins killed several New Republic officials and commanders including Hostis Ij but failed to kill Chancellor Mon Mothma. The New Republic authorities managed to subdue the prisoners. Investigations by the New Republic Security Bureau and the slicer Conder Kyl uncovered the brain steams. However, they malfunctioned as some kind of planned degradation before the New Republic could conduct further investigations.