Washington ? Leading experts on Internet security are skeptical that the FBI and other investigators will be able to track down the person responsible for last weekend’s attack on the Internet.

These experts, including many who provide technical advice to the FBI and other U.S. agencies, said exhaustive reviews of the blueprints for the attacking software are yielding few clues to its origin or the author’s identity.

“The likelihood of being able to track down the specific source of this is very unlikely,” said Ken Dunham, an analyst at iDefense Inc., an online security firm. “We don’t have the smoking gun.”

Unlike attacking software used in some previous high-profile Internet disruptions, the latest code is exceedingly condensed and doesn’t include references to hacker aliases or locations.

It also used a transmission method that made it especially easy for its author to throw off investigators by falsifying his digital trail.

The blueprints for the destructive “Love Bug” virus, which was unleashed in May 2000 by a Filipino computer student, included references within the computer code to his classmates and the university he attended.

Those mistakes helped U.S. investigators track him within 24 hours.