ATLANTA -- CBS Atlanta is asking Tough Questions about the credentials of the self-proclaimed "World's No. 1 Hacker." Gregory D. Evans, of Atlanta, has appeared on numerous national and local news programs to speak about Internet security issues. But an investigation has revealed his questionable past, uncertain credentials and allegations of plagiarism.

In 2002, Evans was convicted on federal wire fraud charges in California and sentenced to two years in prison. He was ordered to pay about $9 million in restitution. Federal court officials told CBS Atlanta, Evans is not current with his payments.

Since his release, Evans started two companies that are publicly traded. Ligatt Security International is a computer security firm. Spoofem is a company that offers technology to disguise a user's phone number on caller ID. That practice has recently been outlawed in the United States.

Evans is now dealing with accusations that he plagiarized his 2010 self-published book, 'How To Become The World's No.1 Hacker.'"

"The vast majority of the book was direct plagiarism from a number of sources," said security consultant Ben Rothke. Rothke, of New Jersey, wrote a review of Evans' book. "We’re talking 70 to 80 to 90 percent in some cases complete chapters cut and paste the works of other authors and all of these works unattributed," said Rothke.

CBS Atlanta has also learned Evans may have used official information from the Department of Defense in his book. According to a flier posted at a recent DOD conference, Evans "published unlawfully obtained information" from a previous conference.

When asked by CBS Atlanta reporter Jeff Chirico whether he plagiarized, Evans replied, "Didn't I say go talk to my lawyer? You know I didn’t plagiarize that." But Evans admits to suing his critics. "Everybody who said I plagiarized, I sued them."

The lawsuit was dismissed in Gwinnett County Court last year. Court records show Evans has a history of suing people who cross him.

CBS Atlanta also found threatening and bullying messages to his critics on Evans' Twitter accounts. Ironically, he volunteers to speak to high school students about the dangers of cyberbullying.

CBS Atlanta has also learned although Evans claimed to be the "World's No. 1 Hacker," he is not certified as an ethical hacker.

"From the research I’ve done, it’s a lot of hype built on more hype," said cyber security expert Chris John Riley. Riley questions what protection Ligatt Security can provide to clients.

Riley said, "I’m worried that people are using this service, believing they are secure."

Evans' critics have launched websites attempting to discredit him but Evans' marketing machine powers through the critics. It lands him as a guest on CNN and Fox News, infuriating others in the information security industry.

Recently, some critics apparently hacked into Evans' own computer system, retrieving thousands of Evans' personal and professional e-mails.

An attorney from the law firm Evans said represented him did not return CBS Atlanta's call.