Bryan Cranston in ‘deep despair’ over death of Breaking Bad co-star RJ Mitte

Bryan Cranston said he is in “deep despair” following the death of his on-screen son and Breaking Bad co-star RJ Mitte.

The 34-year-old’s death was announced by his representatives on Monday, according to reports.

Mitte rose to fame in his role as Walter White Jr in the Emmy-winning series, and used his platform to advocate for disability rights from his experience of living with cerebral palsy.

In an emotional Instagram post, Cranston said the pair had exchanged text messages in recent weeks and tried to arrange a catch-up.

He wrote: “I’m in deep despair as I write this tonight. 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.

“Born with Cerebral Palsy, he never – ever – allowed that challenge to be an excuse for anything. “

Cranston continued: “He met the demanding shooting schedule head on with great determination.

“Always listening to the advice that his TV parents (Anna Gunn and myself) gave him – but being a teenager, sometimes mischievously ignoring the counsel in order to learn the hard way… He was one of the stars of a hit TV show – but still a kid.”

Mitte, real name Roy Frank Mitte III, was an actor and producer who started his career in entertainment playing minor roles in sitcoms such as Everybody Hates Chris and Hannah Montana.

He made a name for himself in 2008 after landing a lead role in hit crime series Breaking Bad, starring as the son of mild-mannered high school chemistry teacher Walter White, who transforms into a ruthless drug kingpin.

Mitte first appeared in the series aged 15 and had a recurring role until its conclusion in 2013, featuring alongside Hollywood stars such as Cranston and Aaron Paul, as well as Anna Gunn, Bob Odenkirk and Dean Norris.

Norris, who played Mitte’s uncle and DEA agent Hank Schrader on Breaking Bad, described the actor as a kind of son to him in a tribute on his social media.

“Oh my God! Was working (and) just found out about RJ. I am heartbroken,” Norris wrote.

RJ Mitte was diagnosed with cerebral palsy aged three (PA)

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“Though RJ didn’t play my TV son, I always looked out for him as a young kid on set. He was a sweetheart of a young man and will be greatly missed. This is so heartbreaking, I can’t believe it. Thinking of him and his family.”

Paul, who played drug user turned drug dealer Jesse Pinkman, said in a statement to The Hollywood Reporter: “I am at a loss. I am heartbroken over this news. RJ, I love you my friend. You will be missed. And to whoever happens to be reading this, please know you are loved, and you are not alone. Always remember that.”

Mitte also landed TV roles in Switched At Birth, Vegas, Now Apocalypse and Chance, and has featured in films such as Time Share, Dixieland and Westhampton.

During his varied career, Mitte walked the catwalk for a Vivienne Westwood fashion show, and also presented part of Channel 4’s coverage of the 2016 Rio Summer Paralympics.

Mitte has also appeared in several music videos, working with the likes of English band Nothing But Thieves and US rockers Hollywood Undead.

At the age of three, he was diagnosed with cerebral palsy, which the NHS describes as the name for a group of lifelong conditions that affect movement and co-ordination caused by a problem with the brain that develops around birth.

Mitte was outspoken about his disability and passionate about using his platform as an actor to educate and inform viewers.