As a criminal probe was under way into the death of Hannah McGuire, her killer ex-boyfriend was allegedly sending menacing letters to a witness he believed was involved in the investigation.

On Monday, Lachlan Young lost a bid to keep these witness intimidation and harassment charges kept secret.

The revelation comes after he ended his Supreme Court murder trial in July after eight days when he abruptly pleaded guilty to murdering McGuire.

The 23-year-old Sebastopol man had been on trial after the prosecutor rejected his guilty plea to the lesser charge of manslaughter.

Young appeared before Ballarat Magistrates Court via video link on Monday to face six charges of witness intimidation and harassment.

The hearing was adjourned to January 29, until after his sentence has been handed down.

Young allegedly intimidated a witness whom he believed was involved in a criminal investigation and is accused of harassing the victim by sending menacing letters about July 23 last year, court documents revealed.

Details of these charges were previously prevented from being aired publicly until the jury in Young’s trial had reached a verdict or if he pleaded guilty to murder.

Defence lawyer Ryan Robertson on Monday opposed a request to reveal Young’s separate charges until his client had been sentenced in the Supreme Court.

He said no details of these alleged offences have been read out in court and Young is yet to enter a plea.

“It is somewhat premature to release that at this stage. There’s no burning urgency for this material to be disclosed,” Robertson said.

Magistrate Mike Wardell allowed the information to be reported, citing public interest following the murder charge being resolved.

The body of 23-year-old McGuire was found inside her burnt-out car in regional Victoria on April 5 last year, two weeks after her relationship with Young had ended.

After killing McGuire, Young tried to stage her death as a suicide and pretended to be her in text messages to her parents before also transferring $2000 from her bank account to her mother and $5000 to himself.

Evidence from the murder trial revealed McGuire had been “terrified” of Young and had sought help from the police in February 2023, telling them his “controlling and turbulent” behaviour was escalating.

Days before her murder, Young had told a workmate that he planned to drug McGuire, drive her somewhere and crash the car while she was unconscious.

The victim had gone to their joint property to meet with Young but never left, and it is believed she was murdered between 1.50am and 2.53am on April 5 last year.

Before he changed his plea, Young had claimed McGuire’s death was an unplanned and spontaneous event after he had forcibly pushed her during an argument, causing her to fall and fatally hit her head on the bathroom floor.

He will face a pre-sentence hearing for the murder charge in October before returning to Ballarat Magistrates Court in January to face the separate charges.

1800 RESPECT (1800 737 732), Lifeline 13 11 14, Men’s Referral Service 1300 766 491