Per the UK Telegraph and The Independent, the pencils, from Hirst's Pharmacy installation, are allegedly worth £500,000 and were kidnapped by the teen, Cartrain, as part of an effort to obtain the return of the teen's artworks, collages that included images of Hirst's For the Love of God.
According to The Independent, "Hirst reported [Cartrain] to the Design and Artists Copyright Society and a string of legal letters were sent to [his] art dealer, Tom Cuthbert, at 100artworks.com, about the teenager's pieces, also called For the Love of God. The online gallery surrendered them to Hirst with a verbal apology." [Emphasis supplied.]
As of this writing, however, 100artworks.com is still offering several of the offending collages for sale; in fact, in its description of the piece at left, the dealer provides a link to an earlier article in The Independent concerning Hirst's supposed objections to the work.
UPDATE: The New York Times reports that Cartrain and his father have been arrested.