Ever since Saarek was a small child, he possessed the ability to telepathically commune with the dead. As an adult, he was chosen to serve in the second iteration of the Green-Lantern Corps. Saarek's ability brought him into contact with another GL named Morro - the caretaker of the Green Lantern Crypt on Oa.
When an alien threat began slaughtering family members of various Green Lantern rookies, Saarek's expertise was called upon to identify the victims and analyze the situation. After literally bathing in the severed eyeballs of dozens of victims, Saarek determined that the beings responsible were a sub-group of the Sinestro Corps known as the Quintet.
Not too long after this, he was commanded by the Scarred Guardian to search and contain the spirit and armor of the Anti-Monitor in a secret solo mission. However, he eventually found Green Lantern Ash, apparently following the same orders, down to the part where he believed he was acting alone. They did not get along, as Saarek channeled the spirit of Ash's beloved to try to soothe him and dissuade him from continuing his destructive vengeance quest.
In the end, both made their way to Ryut and found the spirit of the Anti-Monitor imprisoned within the Black Power Battery, and Saarek collapsed due to the strain of the countless deceased screaming in his ear. Soon after that, they were attacked by a pair of huge rotting hands and both died. Both were seen in Coast City at the summoning of Nekron, turned into Black Lanterns.