In the earlier seasons of CSI, it becomes clear that Gil is also beginning to lose his hearing as well; eventually he requires surgery to fully restore his hearing. Grissom earned his Bachelor of Science degree in biology magna cum laude from the University of California, Los Angeles (UCLA), and his Ph.D. in Biology from the University of Chicago. He became a forensic entomologist. In the episode "Grissom vs. the Volcano", Catherine tells the story of losing at a science competition as a child against a "kid with some lame red ants." Later in the episode Nick also reveals that he lost a science competition and Grissom tells him to let it go. In his childhood science competition, Grissom was the kid with the ants. In the season two episode "Bully for You", he told Warrick that in high school he was a "ghost" (meaning that he did not belong to any group in particular). When he was in college, Grissom financed his first body farm with his winnings from a high-stakes poker game. At the same time, he also attended boxing matches to learn about the patterns of bruise formations on bodies and eventual blood spatters from the injuries. Career Grissom became a crime scene investigator around 1985 (Grissom mentioned in "Living Doll", which first aired on May 17, 2007, that he had been a crime scene investigator for 22 years). Grissom once mentioned losing a body while in Minneapolis, implying he spent time there before taking a job in Las Vegas. This was mentioned again when he works with his former mentor, Dr. Phillip Gerard, played by Raymond J. Barry, stating that he used to work for him in Hennepin County, whose seat is Minneapolis. He became the night shift team supervisor for the Las Vegas CSI unit on the second episode of the series, after Jim Brass was demoted following the death of co-worker Holly Gribbs. In season seven, Grissom took a sabbatical to teach a class at Williams College in Williamstown, Massachusetts, for four weeks. Prior to his sabbatical, Grissom had been showing signs of "burnout." Upon his return, however, he appeared reinvigorated and told Warrick Brown that he "missed" Las Vegas. After the resignation of Sara Sidle, his fiancée, from the lab, and the murder of Warrick Brown, his burnout seemed to be resurfacing. This is particularly evident in "Say Uncle", where, at the end