PARIS – A determined French 16-year-old accomplished a mystifying feat by translating all 759 pages of “Harry Potter and the Deathly Hallows” within days of its July 21 release and posting it online.

The problem: It was illegal, and now the teen has spent a night in jail and faces charges of intellectual property violation.

Author J.K. Rowling’s lawyers say networks of other illegal Potter translators span the world, seeking to profit from the boy wizard’s global appeal, and growing more sophisticated with every new tome.

The French teen translator, a high school student from Aix-en-Provence in southern France, likely had less sinister intentions.

“He just wanted to get the book online,” and did not appear to be seeking commercial gain, Aix prosecutor Olivier Rothe said Wednesday. The boy apparently compiled the entire translation himself, Rothe said.

The teenager, whose name was not released because he is a minor, was picked up Monday following a complaint from police in Paris and was released Tuesday after questioning, Rothe said. He said the boy could face charges for violating intellectual property rights.

The French agency for fighting counterfeiting alerted Rowling and Gallimard Jeunesse, the publishing house that is releasing the official French translation on Oct. 26, of the unauthorized version, Gallimard said in a statement Wednesday. The publishing house said it offered its support to the agency’s investigation.

Gallimard spokeswoman Marie Leroy-Lena said official Harry Potter translator Jean-Francois Menard is still working on “Deathly Hallows,” since he only received the official English version when it was released July 21. Menard refused to comment on the pirated version.

Readers eager for the seventh and final Potter adventure are frustrated that it is taking him so long.

“To wait three months to have a French version, that is too much!” said Ketty Do, a 17-year-old, flipping through the English version at a bookstore on the Champs-Elysees.

Do called the teen translator “a courageous person,” but added, laughing: “Still, I will wait for the official version, since this kid is only 16.”

Twelve-year-old Robin Gallaud, looking at video games in the bookstore, had no such reservations. “If I find the French version on the Net, I will read it,” he said.

Some French bloggers lamented the shutdown of the pirated translation site, though fragmented translations are still available elsewhere, including one by a 54-year-old author who published the final 10 pages of the book in French on his blog.

Neil Blair, a lawyer at the Christopher Little Literary Agency, said Rowling’s agents were “heartened” that the French authorities took action against the teen “to protect copyrights and to avoid innocent fans being duped.”

Blair said French police had identified an organized system of online translation networks where unofficial translations of Harry Potter are posted onto Web site networks and then onto peer-to-peer networks. The managers of these networks derive profit by attracting advertisers. Blair said French police told him one young woman had been questioned about these networks, but was released.

“The real Harry Potter fans are not supporting this,” Blair said.

Such translators are becoming more organized as each new book is released and as the Internet and file-sharing becomes more prevalent, he said.

Fans in several countries have already posted unofficial translations of the “Deathly Hallows” online, including in China, where publishers fear it could lead to counterfeit books in a country where piracy is rampant.

Worldwide, the Potter books have sold more than 325 million copies, have been translated into at least 64 languages, and have been spun off into a hit movie series.

Many French readers already know how “Harry Potter et les Reliques de la Mort” – as it is titled here – ends. Le Parisien newspaper revealed it in an article it printed upside down.