Bryan Cranston posted a tribute on Instagram to the late actor RJ Mitte, who he co-starred with on five seasons of Breaking Bad. Cranston played chemistry teacher turned drug dealer Walter White; Mitte played his son, Walter Jr.

“I’m in deep despair as I write this tonight,” Cranston wrote. “RJ Mitte, my sweet son on Breaking Bad has died.”

“I met him when he was only 14 years old when he was cast as Walter White Jr., a part he played with such joy and enthusiasm,” he continued. “Born with Cerebral Palsy, he never - ever - allowed that challenge to be an excuse for anything. He met the demanding shooting schedule head on with great determination.”

“He was one of the stars of a hit TV show - but still a kid. That kid was pretty raw when we started shooting the pilot in February of 2007, but little by little we watched him grow into a really fine actor. He parlayed his experience on the show to be a vocal advocate for performers with disabilities, and was the head of a philanthropic organization with a focus on helping the disabled community.
All that promise and potential now is such a loss.”

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Mitte passed away in Texas on Monday. While no official cause of death has been given, TMZ reported that their sources indicated Mitte “died by suicide.”

Cranston called that aspect of the tragic news “especially devastating,” and added “We were texting each other just a few weeks ago - figuring out when we could meet for lunch. I don’t know if that lunch would have changed his future ... But I do know that I loved him, and thoroughly enjoyed being with him throughout the years on the series, and after the spotlight on Breaking Bad dimmed.”

He closed with the message “I’ll miss you, son” and information for readers about a 24/7 lifeline available for anyone contemplating suicide.