Did Late Actor Michael Landon Get Cancer from Filming Close to a 'Contaminated' Nuclear Site?

Nearly 30 years after Michael Landon's shocking death, details surrounding the Little House on the Prairie star's health are being investigated.

At the young age of 54, Landon died on July 1, 1991, from pancreatic cancer, just months after his diagnosis. And on Sunday, Reelz Channel will air its Landon-focused episode of Autopsy: The Last Hours of…, which investigates the proximity of the Little House on the Prairie set to the Santa Susana Field Laboratory, where there was a "partial meltdown of a nuclear reactor" in 1959, according to California Department of Toxic Substances Control.

"For nine years, Little House on the Prairie was filmed just 15 miles away from the Santa Susana Nuclear Laboratory," a narrator says in PEOPLE's exclusive sneak peek of the special.

According to costar Karen Grassle, who played Caroline Ingalls, "it took months and months for us to find the right outdoor location" to film the show, which ran from 1974–83. "Finally, this ranch was found out in Simi Valley," she explains. "It was perfect for us."

But "when hundreds of local residents started suffering from cancer, scientists discovered that the Santa Susana lab had been the site of the worst radioactive disaster in U.S. history and that years of contamination had prompted a cancer epidemic," the narrator says in the clip.

As a result of the "cancer epidemic," numerous studies were performed on the area.

"Studies have concluded that this was responsible for up to 2,000-cancer-related deaths and lead to a 60 percent increase in cancers such as lung, bladder, kidney, liver, blood, lymph node, upper digestive track and thyroid cancers," says forensic pathologist Dr. Michael Hunter.

But after examining the Report of the Santa Susana Field Laboratory Advisory Panel from October 2006 and Landon's autopsy results, Dr. Hunter doesn't believe there's a connection between the location of the laboratory and Landon's cancer.

"Despite the scientific studies linking proximity to the site with elevated cancer rates, there is no scientific evidence to suggest that Michael's pancreatic cancer was caused by him working so close to the contaminated area," says Dr. Hunter.

He adds: "Although I can't rule it out entirely, I have found another, much more compelling and direct cause of his cancer."

Years after Landon's death, on March 27, 1992, the California Department of Health Services (CDHS) "released a report that examined the incidence of cancer among residents of Los Angeles (1978 to 1988) and Ventura Counties (1988 to 1989)," according to the government website.

According to the report, residents "living near the SSFL were not at increased risk for developing cancers associated with radiation exposure."

"Cancers were divided into three groups of very radiosensitive (thyroid, bone & joints, all leukemia, excluding chronic lymphocytic leukemia), moderately radiosensitive (breast, lung & bronchus), and possibly radiosensitive (esophagus, stomach, liver, brain & other nervous system, urinary bladder, other urinary system, salivary gland and parathyroid, and multiple myeloma)," says the website.

It continues, "The analyses found that people living near the SSFL were not at increased risk for developing cancers associated with radiation exposure. The analyses suggested that male residents living in Los Angeles County near SSFL may have had an increased rate of bladder cancer relative to residents living elsewhere in the county. There was also an increased proportion of lung cancer among Ventura men."

After the discovery of Landon's cancer in 1991, which had spread to his liver, the actor retreated with his third wife, Cindy, then 34, and their two young children to his 10-acre Malibu ranch, where he girded for the battle with a vegetarian diet, a program of vitamins, enzymes and acupuncture.

He underwent chemotherapy on April 18, 1991. In early May of that year, he submitted to an experimental procedure involving intravenous administration of a cancer-fighting drug.

These treatments had little chance of success. Only three percent of pancreatic cancer patients and five percent of liver cancer sufferers survive for five years. According to the American Cancer Society, studies link smoking and alcohol use with these forms of malignancy. Landon had also admitted that he indulged too much in both.

Over his last days, his condition deteriorated rapidly. On his last weekend alive, Landon gathered his inner circle at the ranch, including Cindy, all nine of his children, longtime friend and business partner Kent McCray and his wife.

They kept a vigil in Landon's upstairs bedroom, where very near the end, according to McCray, Landon said, "I love you all very much, but would you all go downstairs and give me some time with Cindy." She was the only one with him when he died, at around 1:20 p.m. on Monday, July 1, 1991. Landon's body was cremated the next day.

Autopsy: The Last Hours of… airs Sundays (8 p.m. ET) on Reelz.