His attorney, public defender Jay Rorty, confirmed to ABC News that the charges were dropped on Nov. 22, but he refused to say why.
Google, whose complaint originally launched the investigation, said the decision came from the U.S. Attorney's office.
"We didn't drop the case. It was dismissed by the prosecution," Google spokesman Barry Schnitt told ABC News.
"The case was dismissed … at our request," said Matt Parrella, chief of the Computer Hacking and Intellectual Property Unit at the U.S. Attorney's Office in San Jose, Calif.
But as far as the reasons for the dismissal, Parrella had no comment.
Nor was there any clue from the Secret Service, which spent roughly a year investigating Bradley and ultimately arrested him in May 2004.
The Secret Service, in addition to protecting U.S. leaders and visiting diplomats, is responsible for criminal investigations into various types of fraud and money laundering.
One theory: Google didn't want the case to go to court. Fiercely secretive about its methods of curbing click fraud, Google might have feared that if the case went to trial, those methods would have been up for examination -- and a matter of public record.
"I think that the one plausible explanation is that Google did not want any information about its technology to get out into the public," said Brian Kabateck, a class action attorney who represented thousands of small businesses in a lawsuit against both Google and Yahoo.
Schnitt admits that concern about revealing company secrets played a role in the decision.
"We can be asked for information that reveals too much to potential fraudsters," the Google spokesman said. "We need to weigh the benefit of catching one perpetrator against the risk of engendered other perpetrators."
Another possibility, suggested by Schnitt, is that Bradley wasn't as much of a threat as he portrayed himself to be.
"To prove extortion, you have to prove the technology he had could have caused damage," Schnitt told ABC News.
Although Bradley tried to use click fraud as a weapon against media monolith Google, it's mostly affecting small businesses across America.
Click fraud affects a business in two ways.
The first is when someone repeatedly clicks an advertiser's link, essentially blowing its advertising budget with no sales to show for it.
The other, more complicated, occurs when a third party Web site posts an advertiser's link and thus benefits every time someone clicks on a link from that page.
It stems from the practice of pay-per-click advertising or PPC. When computer users click on a sponsored link, the company has to pay a fee to both the search engine and the Web site.
The search engine makes money, the Web site makes money. But the business advertising loses.
It's called "content match," a term Jim Hill is all too familiar with.
Hill, an athletic equipment retailer in Eugene, Ore., quickly recognized that something was fishy when his entire advertising budget for the week was blown in an hour.
"In literally one hour [my whole advertising budget] was wiped out," he said. "I dug deeper and deeper, and I found out that all those clicks came through their content match."
Not only does Hill lose money, but valuable retail ad space is taken away.
Click fraud is particularly a problem for small companies with fierce competitors, disgruntled employees or customers seeking revenge. Their vengeance, with the click of a mouse, is to make that company pay.