FBI agents remain in the country as they work with the police in Auckland following the arrests of senior executives of an internet company accused of piracy.
Police removed computers and hard drives from the home of arrested internet millionaire Kim Dotcom as they wound up their search of the large Auckland property.
Mr Dotcom, who founded one of the file-sharing site Megaupload, was arrested on Friday morning at his property in Coatesville, about 30km northwest of Auckland, as part of a US-led operation against international internet piracy.
Also arrested in raids of 10 properties in Coatesville and Orakei were three others involved in the site.
The police made the arrests at the request of United States officials, who are accusing the company of pirating films and other content, costing copyright-holders more than $US500 million in lost revenue.
Two sawn-off shotguns were among items discovered at the property and seized.
Police also seized assets including luxury cars with an estimated value of $6 million and artworks.
Detective Inspector Grant Wormald who has been overseeing the operation, says the FBI agents will remain in the country for several more days.
"They're working hard with us. Obviously they don't have powers to execute any of their normal activities as they would in the United States, but certainly they've been integral in both the investigation and assisting us with managing how we were to terminate the job."
Mr Wormald said officers removed further items before concluding their search of the property just before midnight on Friday.
"The main components were computer equipment, hard drives and documentation relating to the allegations made," he said.
A police spokesperson says the residence has been returned to the company operating its security and it is now up to the owners to decide what should happen with members of Mr Dotcom's family who are still there.
The chief executive of Internet New Zealand, Vikram Kumar, says Megaupload was used for both legal and illegal purposes
"The legal part of it is, a business wants to share a particularly large file or a photograph, then instead of emailing it to everyone, they would upload it and share the link instead. That's a perfectly legal use.
"On the other hand, there was quite a bit of pirated television shows and movies, and they would be uploaded essentially by people who had this copyright-violated material."
Barricaded in safe room
Police say Mr Dotcom locked himself inside the mansion when members of the armed offenders squad arrived in two helicopters to make the arrests on Friday morning.
While officers undid the locks, Mr Dotcom barricaded himself into a safe room built into his bedroom.
Officers then cut their way into the safe room, where, they allege, they found the German national with a loaded gun close by.
Mr Dotcom was on Friday remanded in custody by a judge at North Shore District Court who said it was too late in the day for applications for bail to be heard.
Also remanded in custody were the website's co-founder and chief technical officer Mathias Ortmann, 40, and chief marketing officer Finn Batato, 38, both from Germany, and Dutch national Bram van der Kolk, 29, also a New Zealand resident who oversees programming.
The US-based lawyer for Megaupload says the company is a legitimate business and will vigorously defend itself against the copyright infringement allegations and the other charges.
The Megaupload site, based in Hong Kong, had around 150 million users and 50 million daily hits, the BBC reports..
It has received celebrity endorsements from artists such as Alicia Keys and Kanye West, making it one of the internet's most high profile file-sharing platforms.