In what prosecutors are calling the first U.S. conviction for theft of an Internet domain name, a Union Township, N.J., man pleaded guilty Monday to stealing a web address and selling it on eBay to an innocent buyer: former professional basketball player Mark Madsen.

Daniel Goncalves admitted to Superior Court Judge Stuart Peim that he stole the address, www.p2p.com, in 2006 by hacking into the account files on the website of GoDaddy, an authorized domain name registrar, and altering the registration information to transfer ownership of the domain to himself.