Ex-FBI agent: Knox shouldn't have been charged

The case of Amanda Knox has been followed the world over. From her conviction to the current appeal trial, many have wondered whether things could turn around for the American college student.

Retired FBI agent Steve Moore has kept close tabs on the investigation into the 2007 murder of Meredith Kercher from the very beginning. He's done his own probing, and has followed the court cases closely.

Initially, Moore thought Amanda Knox was guilty, but when he began digging into the evidence, he changed his mind.

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"My initial belief that she was guilty was simply my confidence in fellow officers around the world," he tells "The Early Show." "If they said she was guilty and if they said they had the knife and if they said she bought bleach, then obviously, the evidence was there."

"When I looked at the evidence, when I saw the crime scene and realized no bleach had ever been used to clean that crime scene, when I saw that the knife was too big to have inflicted the wounds they say it inflicted, and then I knew that the prosecutor was still saying these things when he had to know they were false, I knew there was something seriously wrong with this case."

Upon gaining access to the evidence, Moore says he thought Knox and her former boyfriend, Raffaele Sollecito, should have been eliminated as suspects from the beginning of the investigation by the prosecutor.

Moore says, "They should have been eliminated on day one, but on day five, before the physical evidence came back, the prosecutor had already decided, 'These must be the people, because I know these things intuitively.' That would be like you walking into a doctor with a pain in your chest and him saying, 'I need no tests, I know that you have indigestion.' You would want more investigation than that. And so, what he did is he arrested them. The tests came back and it was completely opposite what he thought, but he wouldn't back down. That's why we're here four years later."

Rudy Guede, of the Ivory Coast, has already been found guilty of the murder and is serving a 16-year sentence. CBS News correspondent Charlie D'Agata reports Knox's lawyers say Guede acted alone in killing Kercher when she disturbed him during a botched robbery. But Guede contends Knox and Sollecito took part, too.

Prosecutors say Knox and Sollecito staged the break-in to cover their part in the murder.

Prosecutors told jurors the Italian justice system is on trial in this case, and their decision would render honor to the country.

So is this appeal trial more about the justice system or is it more about evidence?

"It was about evidence (in the last trial) and (the jury) disregarded it," Moore says. "The only thing the prosecutor has ever said that I believe is true is what he said today, the Italian justice system is on trial. It absolutely is. And every country has problems in their judicial system. The judgment about their system is whether they fix them, and today and this week and on Monday, we will find out if the Italians can fix it."

Moore says he hasn't tried to influence the Italian attorneys, but his views are well-known. He said he has spoken with Knox's family.

"I am not here to try and influence their attorneys," Moore said from Perugia, Italy. "I am here to provide any kind of assistance, any kind of advice."