Jethro - who also sometimes used the surname Cave - was born in 1991 and lived in Melbourne, Australia, working as an actor, photographer and model.
Jethro had been jailed in April after pleading guilty to violently assaulting his mother, Beau Lazenby. His imprisonment came despite his lawyer Sean Ghattas arguing he had been diagnosed with schizophrenia and the attack was a result of his mental health condition.
Jethro lived in Melbourne, Australia, working as an actor, photographer and model. Photo / Getty Images
Jethro had been released from Melbourne Remand Centre last Thursday, May 5 after a magistrate ordered he undergo substance abuse treatment and avoid contact with his mother for two years.
Cave's loss comes seven years after his son Arthur - whose mother is the 'Into My Arms' singer's wife, model Susie Bick - died in July 2015 after falling from a cliff in Ovingdean, East Sussex, at the age of just 15.
Speaking previously about how he and his wife were coping with their grief, Australian singer Cave said: "Two days after our son died, Susie and I went to the cliff where he fell. Now, when Arthur was a small child, he always, always, had a thing about ladybird beetles. He loved them. He drew them. He identified with them. He constantly talked about them.
"As we sat there, a ladybird landed on Susie's hand. We both saw it, but said nothing, because even though we knew the sad significance of it, we were not about to belittle the enormity of the tragedy with some sentimental display of magical thinking. But we were new to grief."
Cave is set to release the memoir 'Faith, Hope and Carnage' about the years following Arthur's death this September.
The book will focus on Cave's life as he tries to come to terms with his grief and it will be written from more than 40 hours of interviews with The Observer journalist Sean O'Hagan.
