University of Otago Clocktower Building where exams were taken from the Examination Office.

A woman hid in an Otago University cleaner's cupboard with an axe until the building closed, emerged after dark wearing rubber gloves and a balaclava and stole almost 100 exam papers.

The 23-year-old woman, who has name suppression, pleaded guilty when she appeared in the Auckland District Court on Tuesday, after her case was transferred from Dunedin.

She will be sentenced on February 10.

Hamish McNeilly The examination office in the University of Otago Clocktower

The police summary of facts said the woman went to the university on November 7 with a pair of rubber gloves, a hooded top and a balaclava. She entered the historic registry office during open hours and hid in a cleaner's cupboard.

After the building was locked, the woman used an axe to smash wood panelling and glass to gain access to various offices.

A silent alarm was triggered when she used a doorstop to wedge open the basement door.

She activated another alarm when she entered another area after using a hand truck to try and lift an office door off its hinges.

The woman looked for exam scripts from her subject area and eventually found them.

She also took 97 other exam scripts from dentistry, English, political studies and health.

Returning home she changed her clothes and drove to Ravensbourne where she threw the stolen exam scripts in the water of Otago Harbour, also discarding footwear and clothing.

Three days after the break-in, the university confirmed 98 unmarked exam scripts, held on the Saturday which was the last day of exams, had been stolen.

Those included dentistry papers, 14 from a second year microbiology paper and 42 from a second-year politics paper.

Police said they were working on "lines of inquiry" before the arrest.

The university was understood to have pulled electronic data, including emails and web search history, to help police.

After the arrest, the university issued a statement saying the scripts had been recovered but were in an "unusable state".

A university spokeswoman said after the court appearance that the stolen exams were located "in a secure location and gaining access to them required substantial effort".

"But, as is the case after any serious incident involving a break-in, we are reviewing our security systems," the spokeswoman said.