An emotional Byron Lill read a victim personal statement to the court about what happened to his mum, Muriel Winning.
When Mrs Winning died in 2023 at the age of 61, Mr Lill placed what he thought what her ashes on the windowsill of his home.
Her body was found at the Hessle Road premises 230 days, seven months and 15 days after her death, the court heard.
Her remains were identified through dental records.
Mr Lill told the court: “All the hard work and tireless care we willingly gave mum was for nothing. She protected us her whole life from mistreatment, and it feels that the one time I could repay her and protect her, I couldn’t.
“Bush took this away from me. I work close to the Legacy premises on Hessle Road and drive past it every day.
“Knowing now that Mum was laying inside for almost eight months destroys me.”
He added: “Knowing she was still laying there when Bush smiled and handed me a box he said were her ashes, when she was still only a matter of feet from me, I just can’t accept.”
Mr Lill said: “Bush took advantage of us when we were at our most vulnerable. He abused his position of trust.
“Why? There will never be a good enough answer. There will never be an answer that I can accept.”
