[Ron Ramirez]

Yes, Tommy Rettig passed away in 1996 - he was only 54. He played Jeff Miller through the first third of the fourth season of Lassie (1957-58 ). It was at the beginning of season four that Jon Provost was introduced as Timmy, as Rettig had become too old for his Jeff Miller part - he was nearly sixteen when he was written out of the series after playing Jeff since 1954.

When George "Gramps" Cleveland died during filming of the fourth season in 1957, producers quickly put together an episode where Gramps has passed away and Ellen must sell the farm and move with Jeff to Capitol City. Paul and Ruth Martin buy the farm and adopt Timmy. And to tie it all up neatly, Jeff leaves Lassie with Timmy.

As a programmer for Ashton-Tate, Rettig also worked on dBASE, Clipper and FoxBASE as well as FoxPro.

Rudd Weatherwax, who was Lassie's owner and trainer (there were several "Lassies" throughout the 19 years the show was on TV), passed away in 1985. His son Bob continues to own collies and trains them and other dogs for movies and television.
http://www.weatherwaxtraineddogs.com/

Trivia: Did you know that June Lockhart and Hugh Reilly were not the original actors to play Timmy's mother and father?