Michel Francoise Theodoor Willemyns, 62, attacked his younger sibling Patrick west of Brisbane while suffering a “hyper manic episode” in March 2017, the Supreme Court heard.

After becoming paranoid about his brother, Willemyns struck the 53-year-old with the spanner and stomped on his head repeatedly.

Willemyns stopped at times to talk to his brother, filming it on his phone.

His sibling was too severely injured to respond.

The overall footage lasting about 10 minutes was considered too distressing to be shown in court but was watched privately by Justice Melanie Hindman.

“The video is disturbing to say the least,” Justice Hindman said.

Willemyns drove to his brother’s Karana Downs residence after 9pm and practised swinging the spanner before smashing his way into the residence of his brother who was lying on the couch.

The attack was prolonged and lasted several hours, the court heard, before Willemyns finally left after 5am the next day.

The victim was later found with blunt force injuries over his body, with 10 lacerations on his head alone.

Two blows were so severe that they fractured his skull.

Willemyns’ mental health deteriorated amid escalating alcohol and cannabis use as his personal and professional life unravelled, the court heard.

He became paranoid about his sibling, who was head chef at the Karana Downs Golf Club, and was suffering a hyper manic episode at the time of the attack, the court was told.

Willemyns was kept in a secure mental health facility for two years before stabilising, his defence barrister said.

“He did not intend to kill his brother,” she said.

He has been in custody under medication since his 2017 arrest.

Willemyns had been initially charged with murder but pleaded guilty to one count of manslaughter by reason of diminished responsibility on Friday.

“Good luck Mr Willemyns,” Justice Hindman said after sentencing him to 10 years.