Nineteen-year-old Owen Thor Walker became the subject of a US Federal Bureau of Investigation (FBI) cyber crime investigation spanning the United States, Europe and New Zealand and dubbed "Bot Roast".

New Zealand police finally caught him last year and he admitted to being the ring-leader, code-named Akill, of a group known as the A-Team.

Starting as a 16-year-old at school, Mr Walker designed and planted "botnets" which are a network of hacked computers able to be controlled via the internet by a single computer.

He came up with a system that beat anti-virus software, it spread automatically and it destroyed rival bot codes.

His botnet reached at least 1.3 million computers.

He pleaded guilty to six cyber crime charges but when he ended up in the High Court in Hamilton Justice Potter did not convict him but ordered him to pay a share in damage caused to hacked computers and to stay off computers.

She heard he had been diagnosed with Asperger's syndrome, a mild form of autism often characterised by social isolation, when he was 10.

TelstraClear spokesman Chris Mirams told Fairfax Media's stuff.co.nz that they had contracted with Mr Walker for seminars and advertising which had been completed by late last year.

TelstraClear, a wholly-owned subsidiary of Telstra, is New Zealand's second-largest telecommunications company.

He was still covered by a 12-month contract not to work for software security competitors.

Mr Mirams said he was linked with DMZGlobal, one of Telstra's on-line security products.

He had addressed board room sessions to security, IT and senior management people.

"He was really talking on the cyber threats from his own experience."

"The feedback was very good, he gave very good information," Mr Mirams said.

"It helped companies understand that it isn't an overseas thing; attacks can happen anywhere."

He said it was not the equivalent of hiring a bank robber to advise on bank security.

TelstraClear had spoken with the police who investigated the hacking and they considered Justice Potter's rulings.

They also spoke with Mr Walker and his mother with the purpose of "finding out where his mind was at".

He only gave presentations and was used in an advertisement and he did not have access to computers on the TelstraClear network.

"We found him pleasant to deal with and he genuinely wanted to help New Zealand businesses by sharing experiences."

Mr Walker or his mother Shelley Moxham-Whyte could not be contacted for comment.

stuff.co.nz