He developed hyperacute senses from surviving in the wild, but repressed them when he returned to civilization.

His sensory abilities re-manifested five years later, while conducting an extended stakeout in the forest as a detective in the Major Crimes Unit of the Cascade, Washington, police department.

Jim later marries Carolyn Plummer, another detective on the force. Shortly afterwards, Jim is sent on a solitary stakeout for a week in a remote woodland location, during which his senses start to re-emerge, primarily his sight and hearing.

Their unlikely partnership works, and together they fight crime in the streets of Cascade.

The only person aside from Sandburg who knows Jim's secret is his captain and friend, Simon Banks. During his childhood, he had a friend, Bud who helped him with said senses.

Unfortunately, Bud was murdered at some point, one of many cases of trauma in his childhood.

His mother also left, leaving him to live with his extremely wealthy father, William Ellison, and his brother, Steven Ellison.

He went to a hospital for an examination where he met Blair Sandburg, an anthropologist from Rainier University, whom Ellison initially mistook for a physician.

Upon hearing Ellison's story, Sandburg declares that Ellison is a "Sentinel": in ancient tribes, Sentinels used their enhanced senses to protect their village. Blair had been studying Sentinel mythology for years.

For example in Season 2 Episode 15 "Secrets", Jim's Silver Star medal is shown .

Additionally in the pilot, Jim is shown to be wearing a Combat Infantryman Badge and the Parachutist Breast Badge on his uniform.

The Sentinel is a Canadian-produced television series that aired on UPN in the United States from 1996 to 1999.

It premiered on March 20, 1996, and ran for 65 episodes (four seasons). Jim Ellison was a US Army Ranger who spent 18 months in the Peruvian jungle after the rest of his unit was killed.

Nevertheless, his instincts as a Sentinel remain, leading him to "serve and protect" his "tribe", the residents of Cascade, by joining the police force.