SEATTLE - Researchers at the University of Washington and the University of California, San Diego have come up with a virtual watchdog for your laptop.

The free software, named "Adeona" after the Roman goddess of safe returns, reports the laptop's location when it connects to the Internet.

Posted at http://adeona.cs.washington.edu/, it works by using the Internet as a homing beacon. Once Adeona is installed, the machine will occasionally send its Internet protocol address and related information to OpenDHT, a free online storage network. The information can be used to establish the computer's general location.

On a Macintosh computer, Adeona also uses the computer's internal camera to take a photo that it sends to the same server.

Adeona scrambles the information so it must be deciphered using a password known only by the person who set up the account. If the laptop is stolen, only the original owner can access the location data.

"Adeona is free and easy to install, so anyone who owns a laptop, or even a small company, can use it to track their assets," said co-author Gabriel Maganis, who recently received his UW undergraduate degree in computer engineering. "We're really hoping laptop users all over the world will install it on their machines."

Since Adeona's public release, more than 50,000 people have downloaded the software under the open source license. The current version works on desktop and laptop machines running Windows, Macintosh or Linux. Researchers say they have already received numerous requests for an iPhone version.