Dotcom, who had his name legally changed, is the former CEO and current chief innovation officer of Megaupload. A resident of Hong Kong and New Zealand, and a dual citizen of Finland and Germany, he made more than 42 million dollars from the site in 2010 alone, according to the indictment.
The 37-year-old, originally named Kim Schmitz, and three other employees were arrested Thursday in New Zealand at the request of US officials. Three other defendants are at large, including one Estonian.
Dotcom, whose mother is Finnish, grew up in Germany. He changed his name to Kim Tim Jim Vestor and became a well-known hacker while still a teenager. As an adult, he set up a data security firm, which he sold for a large profit. Dotcom was later convicted of insider trading and other offences in Germany.
Dotcom's mother and siblings live in Turku, which is his official address in the country. He has not been to Finland in a long time, most recently renewing his passport at the Finnish consulate in Hong Kong.
Lavish lifestyle
New Zealand police said they seized cars worth NZ$6 million (nearly five million US dollars), including a 1959 pink Cadillac and a Rolls Royce Phantom at the "Dotcom Mansion" in Auckland along with valuable artworks.
In addition, NZ$11 million in cash held in New Zealand financial accounts was frozen pending the outcome of legal proceedings, after the suspects were alleged to have made illicit millions from subscriptions and advertising.
In the latest skirmish in a battle against piracy of movies and music, the US government shut down the Megaupload content sharing website on Thursday, charging its founders and several employees with massive copyright infringement.
Hackers responded by attacking the websites of the Justice Department, the world's largest music company, Universal, and trade groups that represent the music and film industries.
Megaupload has some 150 million registered users.