Justice statue
A Solihull busker who heard voices in his head before killing his parents has been given a hospital orderGetty

Cannabis addict Carl Chang stabbed his parents to death at their Solihull home after hearing voices in his head and believing they had bugged his laptop.

The 23-year-old busker killed his mother Quoi, 50, and his father Pin Cheng Chang, 59, at the family home Hermitage Road, Solihull in the early hours of 7 July, 2014.

He was sentenced to indefinite hospital order at Birmingham Court on Monday after pleaded guilty to manslaughter on the grounds of diminished responsibility.

If he is ever deemed well enough to leave hospital, the Home Secretary must authorise his release.

During the investigation it emerged that in the weeks leading up to incident, the former student had stopped busking in Solihull town centre and become a recluse.

Relatives described how Chang, who had dropped out of studying music at the University of Manchester, had amassed a debt of £4,000 and turned to cannabis to "cope with the stress".

Just days before killing his parents, Chang said he heard voices and believed his laptop had been bugged.

On the 5 July he took a coach to visit relatives in London, accompanied by his mother, sister and sister's friend

Part way into the journey, Chang became agitated and told the coach driver that he wanted to get off, threatening him with a penknife if he didn't stop. Police were called and Chang was cautioned.

In the early hours of July 7 West Midlands Police officers, together with ambulance colleagues, were called to the family home following a report Chang had threatened to harm himself.

Following a full medical assessment, a referral was made to his GP and with no crimes committed, officers left.

An hour later, Chang's 18-year-old sister − who had been in bed − heard an argument between him and his mother Quoi. Her mother screamed, prompting dad Pin to run downstairs to his wife and son.

The teenager followed and found her mother injured and ran to a neighbour's house for help.

When officers arrived they found the body of Quoi Chang in the garden and Pin Cheng Chang's body in the living room.

Having killed his parents Chang attempted to kill himself and he was taken to hospital with life threatening injuries. Having been treated for his injuries he was transferred to a mental health unit where he has remained.