The deaths of a prominent couple found unresponsive in their SUV on a California highway appear to be 'medically related,' police said.

Judith 'Judy' Wyler Sheldon, 84, and her husband Wylie Sheldon, 86, were discovered in their Jeep Compass on Interstate 5 near Lake Shasta on Monday.

Sheldon's father, former Army vet William Wyler, directed some of Hollywood's biggest stars – including Audrey Hepburn, Charlton Heston, Barbra Streisand, and Laurence Olivier – during a career that produced some of cinema's most enduring classics. 

California Highway Patrol officers found the couple inside the vehicle with the engine still running shortly before 6pm on one of the hottest days of the year in the region, when temperatures soared to 109F.

Authorities do not suspect foul play and are investigating whether the extreme temperatures may have contributed to the deaths as they await autopsy results.

'It was the hottest day of the year so far, or second hottest. I'm sure there's always a possibility that excessive heat played a role,' Lieutenant Josh Smith of the California Highway Patrol told SFGate. 'But I can't confirm that without a medical exam.'

According to the CHP, Judy Sheldon was behind the wheel while her husband was seated in the passenger seat. The vehicle's engine was still running when the officer approached.

A second officer and emergency medical personnel responded to the scene and attempted life-saving measures, but both were pronounced dead.

'We don't have a lot of information now,' Smith said. 'An autopsy has not been performed yet. We're waiting to hear when they'll schedule that.' 

Smith said investigators are contacting relatives and friends while also retracing the couple's journey from the Bay Area to identify where they may have stopped before reaching the area where they were found.

Authorities said the couple had been traveling to the Oregon Shakespeare Festival in Ashland, Oregon.

Redding and surrounding areas were under an extreme heat warning on the day the couple died.

The deaths have stunned members of California's arts and film communities, where Judy Sheldon had long been a respected figure.

'We are reeling from this news,' Anita Monga, artistic director of the San Francisco Silent Film Festival, said in a statement. 'Judy and Wylie were very dear to us, supportive and a positive presence at all our events.'

For many in San Francisco's cultural circles, the Sheldons were known as much for their hospitality as their philanthropy.

Their home frequently served as a gathering place for visiting film archivists, musicians and cinema enthusiasts attending festival events.

Judy Sheldon spent decades championing silent-film preservation and played a central role in the San Francisco Silent Film Festival. 

After serving as president of the organization's board, she later became its longtime chair.

'I used to joke with her that she was our Frank Sinatra - Chairman of the Board,' Monga recalled.

Monga said the Sheldons regularly opened their home to festival guests and supporters.

'Judy would allow, actually encourage, our visiting film archivists and musicians to pose for pictures with her father William Wyler's Oscars,' she said. 'The perfect hosts.'

The loss was still difficult to process, Monga added.

'I'm sorry to not be more articulate; this loss is so devastating.'

Stacey Wisnia, executive director of the San Francisco Silent Film Festival, said Sheldon was a familiar face at virtually every event she could remember over more than two decades.

'Completely unassuming, she could always be found in the theater lobby engaged in lively conversations with festival musicians, special guests, and audience members,' Wisnia said.

She added that she would miss Sheldon's 'warmth, curiosity, and charming stories about her travel adventures and her father, the great director William Wyler.'

'She was a San Francisco treasure,' Wisnia said.

Born Judith Wyler in Los Angeles, she spent much of her life preserving and celebrating cinema history. 

Although she briefly appeared on screen during the 1950s, earning credits in productions including The Errol Flynn Theatre, The Buccaneers and BBC Sunday-Night Theatre, her lasting legacy came through her work behind the scenes as an advocate for film preservation.

She became especially devoted to protecting silent-film history and played a major role in promoting awareness of early cinema. 

The San Francisco Silent Film Festival lists her as chair of its board, reflecting years of involvement with the organization.

In a 2007 interview, Sheldon explained that her passion for the festival grew after she attended a retrospective dedicated to her father's silent-era films in Pordenone, Italy. 

The experience helped deepen her commitment to preserving a vital chapter of film history.

Her influence extended well beyond the world of silent cinema. She also served in leadership roles supporting San Francisco's cultural institutions and was listed as a co-chair for a gala hosted by San Francisco Performances during its 43rd season.

The loss carries an added historical resonance because of her family's place in Hollywood history.

Her father, William Wyler, an Army vet who served in the Air Force as a Lieutenant Colonel in World War II, remains one of the most acclaimed directors ever to work in American film. 

Across a legendary career, he directed classics including Roman Holiday, Ben-Hur, 

The Best Years of Our Lives, Mrs. Miniver and Wuthering Heights. 

He won three Academy Awards for Best Director, a feat achieved by only a handful of filmmakers.