Editor's note: This story was updated to reflect the show will air on the Investigation Discovery Channel.
On July 21, 1996, Kings Canyon National Park ranger Randy Morgenson tacked a short note to his tent cabin at remote Bench Lake.
It read: "I'm going on patrol. Back on the 24th."
When Morgenson didn't return, park officials mounted a search that lasted more than two weeks and included about 100 people, five helicopters and eight dog teams.
Despite one of the largest search-and-rescue operations in park history, five years passed until the mystery was solved.
Morgenson, and the search for his whereabouts, were the subjects of a 2006 book titled "The Last Season." And now the story will be told in a 60-minute program on the Investigation Discovery Channel.
"Radio Silence," the latest installment of Investigation Discovery's "Disappeared" series, airs 9 p.m. Monday. It will be repeated Tuesday at midnight and Jan. 19 at 5 p.m.
Among those interviewed are China Peak ski patrol director Randy Coffman, a former Kings Canyon district ranger who headed the search for Morgenson.
Coffman, who declined to be interviewed for "The Last Season," said he agreed to participate because he believed the show's producers were set on getting the story accurate while being sensitive to those involved.
In 28 years patrolling the Sierra backcountry, Morgenson built a reputation as a ranger who was not only knowledgable but friendly to backpackers.
Even though Coffman has been involved with hundreds of search and rescue operations, it's different when you're looking for a friend and colleague.
"It sticks out because Randy was one of us," said Coffman, who allowed producers to film interviews in his home and served as a technical adviser. "It's an extreme rarity in this business."
Fresno County sheriff's deputy Eric Schmidt, who until recently led the country's SAR unit, helped producers stage helicopter insertions and extractions near Shaver Lake in order to re-enact parts of the search.
In 2009, Schmidt spearheaded the effort to get Morgenson's name placed on the Peace Officers' memorial at Courthouse Park.
Said Schmidt: "I've already set my DVR so I don't miss it."
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