The director of Shia LaBeouf’s new film has recalled how his intense performance left those on set feeling “scared and hurt” by the experience.

Josh Penn Soskin is the director of The Rooster Prince, a drama based on his relationship with his late brother, David, who suffered from bipolar disorder. LaBeouf was cast as Eli, a character based on David, and in a new article for Variety he recalled how both his grief and LaBeouf’s personal issues drove both men to emotional extremes.

The piece opens with a description of one moment on set where he described the actor as “exploding”. “He was screaming across a parking lot, where his character, based on my brother, was now breaking down,” he recalled. “He’d given a performance so brilliant, and often so meta, that I didn’t cut right away — because we’d lost a clear sense of what was movie and non-movie.”

He continued: “He was in deep pain. In fact, he was in even more pain than all the pain he was causing. This was the kind of pain I had seen in my late brother David’s eyes. Pain I couldn’t fully understand, or even soothe. Pain that eventually took him from me. And now, just three takes in, the scene and the day were over. Those in the blast radius were rightfully scared and hurt. Shia had vanished. The producers were palpably nervous. I was about six inches from a panic attack.”

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Soskin praised LaBeouf’s devotion to his craft. “Shia’s devotion to the work became nearly religious,” he said. “He memorized Dave’s books. Worked night and day. It seemed he rarely slept.” He also recounted the manic relationship between them. “Shia and I could fight terribly one day, and the next find ourselves in a deep embrace, tears streaming down our faces,” he said, “locked into a bond that was so deep it can be only compared to what it felt like to hold my own brother.”

Faced with losing the film due to crew members and producers traumatised by the star’s behaviour, the director recalled delivering a speech that pleaded for “’Maximum empathy’ for the people who had been hurt, and also for those who had done the hurting.” He then described what he viewed as society’s intolerance of severe mental health issues.

“We applaud public figures who confess to anxiety or depression,” he argued. “Not to discount them: I’ve struggled with anxiety for years. But those conditions are easy to destigmatise. Because they’re mostly suffered behind closed doors. But what about the messier ones? Bipolar. Schizophrenia. Personality disorders. My brother sprinting naked through the streets of a foreign city. Or Kanye unleashing on Twitter. Well, that’s not quite as convenient for us.”

The Rooster Prince is currently in post-production.

Shia LaBeouf has experienced numerous legal issues in the past few years, and has made headlines many times for seemingly erratic behaviour. The actor was recently ordered to attend rehab and undergo a drug testing program following his arrest in New Orleans in February. The Transformers star had been visiting for Mardi Gras, and was described by locals as “terrorising” the city. Commenting on the incident, he remarked: “jail be another adventure”.

In April, actor Bryan Cranston joked about LaBeouf’s issues, saying in an interview: “Shia, get some help”.