Bettmann Archive Lee Aaker as Rusty on The Adventures of Rin Tin Tin
Lee Aaker, best known for his role as Rusty on 1950s TV series The Adventures of Rin Tin Tin as a child actor, has died. He was 77.
Paul Petersen, another former child actor, announced the sad news on Facebook Monday alongside a signed youth photo of Aaker with his onscreen canine pal.
"Saying Goodbye to Lee Aaker. You have to be a certain age to remember Rin Tin Tin," wrote Petersen, 75, of the iconic children's adventure-western series on ABC.
Petersen — who is also an author and activist for child actors — went on to share that Aaker died April 1, "alone and unclaimed ... listed as an 'indigent decedent.' "
"As an Air Force veteran Lee is entitled to burial benefits. I am working on that," he added. "God knows when a sparrow falls."
Never miss a story — sign up for PEOPLE's free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer, from juicy celebrity news to compelling human-interest stories.
While The Adventures of Rin Tin Tin, which premiered in 1954 and ran for five seasons, was Aaker's breakout role and the one he is most known for today, he had several other credits before that, both on television and the big screen.
His first role came in the 1951 film Benjy, followed by appearances in movies like The Greatest Show on Earth and High Noon.
Other television credits included turns on Fireside Theatre, The Lone Ranger and, later, The Donna Reed Show.
Walt Disney Television via Getty Images Photo Archives/Walt Disney Television via Getty Images Lee Aaker as Rusty on The Adventures of Rin Tin Tin
RELATED VIDEO: Childhood Star Shirley Temple Dies at Age 85
Aaker's final roles came in 1963: as a student leader in the film Bye Bye Birdie and as Cadet Blake on The Lucy Show.
The actor eventually left acting behind, working as a carpenter for 20 years, according to The Hollywood Reporter.
THR also reports that he spent time as a ski instructor at California's Mammoth Mountain, teaching the sport to people with disabilities and underprivileged kids.