A teenager from New Zealand who was accused of stealing millions of pounds has been let off without a conviction, despite pleading guilty to hacking into computers around the world.

18-year-old Owen Thor Walker, known online as "AKILL", was ordered to pay just £5,500 in costs and damages after a high court hearing in Hamilton, New Zealand, and could even end up working with local police to help them understand online crime.

Lawyers in the case told Associated Press that officers were interested in using Walker's skills for positive purposes, and although Detective Inspector Peter Devoy said that "there is no offer on the table", he admitted that the "option is being kept open".

Walker was arrested in November last year after an investigation involving the New Zealand police, FBI, US Secret Service and Dutch police, and was initially accused of leading a computer hacking ring that had stolen more than £12m from victims around the world.

After a high court hearing, however, police said Walker was in fact employed by the group to write software which they then used to access people's bank accounts. According to police, Walker did not directly take money from people's bank accounts, but the software he wrote was used by other criminals.

Walker pleaded guilty to charges of accessing a computer for dishonest purposes, accessing computer systems without authorisation, interfering with computer systems and possessing software with the intent to commit crime, but Justice Judith Potter dismissed the charges and ordered him to pay damages and costs of $14,000 New Zealand dollars (£5,500).

The case was part of a wider crackdown on the group, which has seen eight people around the world charged or convicted since last year. Arrest warrants have been issued for 13 others.

The group, said police, had built a massive network of more than a million zombie computers – known as a "botnet" – allowing them to steal credit card information, manipulate stock trades and crash the systems of large companies.