A Northland judge has refused to discharge a woman whose obsession with her former employer turned into criminal harassment. 

Sentencing Sin Tin Chang, in Kaikohe District Court, to nine months' supervision Judge Brandt Shortland said it would enable authorities to assist and monitor her after she was released from the Mason Clinic, where she has spent five months - sufficient to cover the punitive aspect of her sentence. 

Supervision would also be a safety measure for the victim and her family, who were significantly impacted by this offending. 

Pointing to the 2011 case of Christie Marceau - a teenager murdered by another teen who was obsessed with her - Judge Shortland said the court could not ignore lessons learned from that case 

Marceau, 18, was stabbed to death at her family's North Shore home by an acquaintance Akshay Anand Chand, who was on bail for previous offending against her and had been ordered by a judge to stay away from her. 

A coroner later found severe inadequacies in District Court and other agency processes, failed Marceau. Major changes to bail applications, file management and accessibility, and communication with victims, was recommended. 

Dealing with Chang, who pleaded guilty to three charges of criminal harassment, Judge Shortland noted it was "not a common crime" in New Zealand. 

Chang became besotted with the owner of a small Northland business, where she worked as a barista for about three months before her behaviour caused her termination. 

Police served her with a trespass notice banning her from the business for two years but Chang breached it that same day. 

Two days later, police served her with a criminal harassment order. 

A month later, she left 25 phone messages on the victim's phone saying she was back in town, wanting to catch up and wanted a relationship with the woman. 

The victim's partner arrived home one morning to find Chang on the doorstep. 

She refused to leave, tried to get into the house, rifled through the mailbox, and took photographs. 

When police arrived, Chang said she was worried because the victim's business was about to close. 

The judge said the consequences of a conviction were not out of proportion to the gravity of the offending, which was moderately serious as evidenced by the maximum penalty for the offence – a two-year prison term. 

Chang had been determined to pursue her "very unhealthy" obsession, despite orders and warnings. 

At one stage she even convinced Covid-19 border control personnel to let her through to Northland from Auckland, saying she needed to be at Whangārei Hospital. 

She was in custody at the Mason Clinic where she was receiving mental health treatment but there was no guarantee she would not reoffend. 

Despite Chang's protestations that she was over her fixation, she still wore a photo of the victim around her neck. 

Whether Chang's visa opportunities would be jeopardised or whether she was deported as a result of the conviction was a matter for immigration authorities – not the court – and the process to deport Chang was already underway, the judge said. 

He was mindful of compelling and mitigating submissions on Chang's behalf – she was remorseful, of good character, and employable. 

"However, one cannot ignore the unfortunate case in recent times of Christie Marceau and, as a result of that case, there has been a heightened need to assess the balance of the risk of harm against justice. That is a matter in which this decision falls upon," the judge said. 

"At some stage, you are going to be released from the Mason Clinic and there has got to be some sort of ongoing support and monitoring," the judge said. 

To discharge without conviction would leave Chang largely unmonitored. 

Once back in the community, she would only be required under the Mental Health (Compulsory Assessment and Treatment) Act, to take medication. 

Intensive supervision would enable authorities to dictate where she lived and assist her until further decisions about her future were made. 

It would also be a safety measure for the victim and her family, who were certainly psychologically affected by the offending, Judge Shortland said. 

A condition of the supervision forbids Chang from travelling north of Warkworth.