Three justices of the Court of Appeal resentenced Peter James Arthur this week to 22 years’ jail with a non-parole period of 18 years for the murder of his housemate.

His original sentence was 16 years with a 13-year non-parole period.

The director of public prosecutions appealed the sentence after deeming it “manifestly inadequate”, arguing that sentencing Justice Lex Lasry had placed too much weight on mitigating factors.

Arthur murdered Ms Kelly in the early hours of January 22, 2016, by striking her to the head six or seven times with a hammer after attempting to drug her in a bungalow at the rear of the property they shared.

The director described Arthur’s crime as “truly wicked” and “heinous” in the submission, and the motive was senseless.

He argued that Arthur’s crime was “at the highest end of the spectrum” for murder.

Adding to the gravity of the crime was the fact that Ms Kelly had an intellectual disability, her four children lost their parent, the crime was planned for weeks in advance, Ms Kelly was aware of the plan shortly before her death and Arthur had attempted to drug her on the night of her death.

Ms Kelly was described as “defenceless”, and the burying of her body in a dry creek bed and subsequent lies about the crime added to the aggravating features.

Defence counsel for Arthur argued the crime was not at the “highest end” of offending for murder. Arthur had also co-operated with police in helping them to find the body of Ms Kelly in a dry creek bed in Shelbourne.

In their judgement, justices Phillip Priest, Barry Beach and Emilios Kyrou found that Arthur had “ample opportunities” to not go through with the attack.

“The judge was right to describe the murder of Ms Kelly as a ‘vicious, calculated and planned killing’ and ‘an extraordinary, calculated and planned attack on an extremely vulnerable woman’,” the judgement reads.

The judgement found that the sentencing judge had placed too much emphasis on mitigating factors, and the crime was at a high end of murder offences.

They described Arthur’s crime as “callous, cold-blooded and senseless”.