Calgary police have arrested one of the world's most notorious computer hackers.

29-year old Ehud Tenenbaum is accused of hacking into a Calgary company's computer system and stealing nearly $2-million.

Tenenbaum gained worldwide attention a decade ago when as a teen in Israel, he hacked into the Pentagon's computer system.

He was convicted for the crime, but also earned admiration in the cyber-world from those who felt Tenenbaum was exposing dangerous flaws in computer systems around the globe.

Calgary police say recently Tenenbaum has been living in Montreal where he allegedly helped execute a massive cyber theft.

He and three other people allegedly hacked into a Calgary company's computer system, artificially inflated the value of their debit cards then withdrew money from ATM's around the country.

Police say the target, a local company, offers pre-paid debit cards.

That's essentially like a gift card you'd get for a store, but it's got cash on it.

They're often used as gifts or just to send somebody money.

Police say hackers managed to manipulate the company's computer system to increase the value of the cards and that even for a computer crime, it was high tech operation.

The hackers either learned or managed to create passwords for the system to get access and then they had free reign.

Police say the company involved did everything right and that it has a good cyber-security system, but it appears not to have been good enough in this case.

"This investigation was a joint investigation involving the Vancouver police, the U.S. Secret Service and the Montreal Police Service. As a result, after a nine month investigation, four people were arrested in Montreal, returned to Calgary and face charges of using these stolen debit cards information as well as fraud."

The three other suspects were arrested with Tenenbaum, but he's the only one still behind bars and he's being held here in Calgary.