The teenage son of Australian rocker Nick Cave fell to his death while under the influence of LSD, a coroner’s inquest in Brighton, England, revealed on Tuesday.

According to testimony, Arthur Cave, 15, took the hallucinogenic drug with a friend prior to his fatal fall on July 15.

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An eye witness described Arthur as “staggering” and “zig-zagging” on the edge of the Ovingdean Gap cliffs on England’s South coast shortly before his death.

Veronica Langford shared the graphic details in the presence of the Nick Cave and the Bad Seeds frontman, 58, and his wife, former model Susie Bick, 46, both of whom momentarily left the hearing when the testimony was heard, the Associated Press reported.

Langford described watching the student climb a public safety fence and walk within a single yard of the 60-foot drop shortly before the accident.

“I was stuck in slow-moving traffic with my 11-year-old daughter as we were coming from a school open evening,” Langford told coroner Veronica Hamilton-Deeley, who recorded an accidental death verdict.

“Because it was so slow, I had time to observe what was going on around me,” she said. “As we approached the top of the hill, I noticed a young man walking – staggering and zig-zagging on the grass. I was concerned and my initial reaction was that he was under the influence of drugs or alcohol.”

The witness explained her reaction when Arthur “slumped down into the grass” and she could no longer see him, saying, “I thought to myself, ‘I need to get to him.’ I said to my daughter, ‘Look sweetheart, we need to go and do our Good Samaritan bit.'”

She added, “My daughter saw him get up and when I looked in my rear view mirror he had come down the bank and over the fence. I had a real sinking feeling at this point.”

Langford, her daughter and a group of other concerned motorists hurried to the cliffs to discover Arthur lying motionless on the concrete below.

Despite efforts to resuscitate him, Cave died that evening at the Royal Sussex County Hospital. The student – a keen drummer who had appeared in the movie 20,000 Days on Earth alongside his father – had broken both legs and suffered a brain hemorrhage and a series of catastrophic skull fractures, a previous hearing revealed.

In the days after the tragedy, Cave released a statement through the police, saying, “Our son Arthur died Tuesday evening. He was our beautiful, happy, loving boy. We ask that we be given the privacy our family needs to grieve at this difficult time.”

Arthur’s twin brother Earl left flowers on the beach where Arthur died. His message read, “Arthur – I love you so much. You were a joy to be around and I will never forget you. You were the best brother I could ever ask for. Earl.”