The prisoner had appeared in the Whangārei District Court prior to testing positive.
The Whangārei District Court has continued to run as scheduled but taken additional precautions after a defendant who appeared in court last week tested positive for Covid three days later.
On arrival at the prison, he was given a Rapid Antigen Test (RAT), initially returning a negative result. But a follow-up PCR test administered the day after returned a positive result on January 31.
The Northland District Health Board were continue to investigate the unlinked case.
Ministry of Justice Chief Operating Officer Carl Crafar said everyone who came into contact with the defendant at the courthouse has been identified and "informed of Healthline advice".
"Cleaning arrangements were made, with the usual deep clean occurring as part of the court's daily cleaning regime.
"Court operations have continued as normal," Crafar said.
The 19-year-old disappeared without her wallet or mobile phone.