Born in 2278 on Vulcan, Chu'lak was commissioned as a Starfleet officer in 2355 with the rank of ensign. After graduation from the academy Chu'lak's first first assignment was on board the USS Strata under the command of Captain Jason Stone. Chulak's service on the Strata was exemplary. The Strata's CMO Doctor Martin Rackham did make a notation that Chu'lak had potential latent psychological instability.
Following his service on the Strata, Chu'lak was assigned as a science officer on board the USS Grissom. Serving on the Grissom from 2365 to 2375. The vessel had a crew of 1,250, of which only six survived when the Jem'Hadar destroyed the Grissom at the Battle of Ricktor Prime, including then Lieutenant Chu'lak.
Even though Chu'lak was thought to be a Vulcan who was unaffected emotionally by the loss of so many crew mates, their deaths caused Chu'dak to experience a psychological breakdown. Not realizing that Chu'lak was now psychotic, Starfleet assigned him to Deep Space 9 under the command of Captain Benjamin Sisko. Chu'lak was assigned quarters on level D of the habitat ring.
Chu'lak was obtained schematics for the experimental TR-116 rifle, which he then to include a micro-transporter and an exographic targeting sensor. This allowed him to see through bulkheads and fire the weapon from the comfort of his own quarters. He soon began killing station residents, choosing his victims on the basis of whether or not they had pictures of people in their quarters who showed any kind of emotion. Hector Ilario, Greta Vanderweg and Zim Brott were all killed by Chu'dak before he was stopped by Lieutenant Ezri Dax. When asked why he had committed the murders, Chu'dak responded he had committed his crimes because "logic demanded it." Much to the disappointment of Joran, Ezri did not finish off Chu'lak, and summoned medical aid.
When the Bajoran Ro Laren arrived on the station following the end of the Dominion War, Quark decided to find out how much she knew about her new assignment. One of his questions was if she knew the identity of the Starfleet officer who had gone on a killing spree in 2375. Ro correctly identified him as Chu'lak, but thought that he was an Andorian, not a Vulcan.