Convicted sex offender Joseph Edward Duncan III (search) spent months on the Internet documenting his internal struggle over right vs. wrong. Then, four days before two Idaho children he is accused of kidnapping disappeared, he wrote: "The demons have taken over."

It was one of the last entries in Duncan's Weblog before the 42-year-old North Dakota man was arrested and charged this week with two kidnapping counts. Authorities believe he took 9-year-old Dylan Groene and 8-year-old Shasta Groene from their Idaho home shortly before their 13-year-old brother, mother and her boyfriend were bludgeoned to death May 16. Police say Duncan also is a suspect in the killings.

"God has shown me the right choice, but my demons have me tied to a spit and the fire has already been lit," Duncan wrote April 24, after he had jumped bail in Minnesota on charges of molesting a 6-year-old boy in a playground.

His last blog entry was May 13, two days before the members of the Groene family and friend Mark McKenzie were last seen alive.

"As far as 'taking people with me,' well, I don't know if that is right or wrong," he wrote. "In fact, I don't know much any more what right and wrong even is."

Duncan was arrested Saturday at a Denny's restaurant in Coeur d'Alene (search) when a waitress recognized the girl with him as Shasta and called police. A body believed to be that of Dylan has been found in Montana and awaits positive identification.

Richard Forno, a computer crimes expert in Washington, D.C., said prosecutors will likely use Duncan's blog as they prepare the case against him.

"This type of information in his blogs, where he's telegraphing things and revealing some of his other issues, certainly that is relevant in a case like this," said Forno.

Duncan's began his "Blogging the Fifth Nail" online journal — the title is an allegorical reference to a fifth nail intended to end Christ's suffering on the cross — in January last year.

Police concluded that Duncan was the author of the journal based on interviews of people who knew him and on the Internet Protocol address — an identifying number specific to a computer — that was used to establish the blog. The entries each include the tag line, "Posted by: Joe."

In sporadic entries usually posted in the middle of the night, Duncan used the digital soapbox to vent his anger over the social stigma of being a convicted sex offender.

"I have decided to give up on trying to convince people that I am a real person, with honest and good intentions, not some evil monster they should be afraid of," he wrote last year.

The entries include excerpts from a book he said he was writing based on his conviction at age 16 in Tacoma, Wash., of sexually assaulting a 14-year-old boy at gunpoint. He documents his nightmares, his anger over serving 20 days past his 20-year prison sentence, his difficulty making friends and dating, and diatribes against police checking on his whereabouts and confiscating his computer and digital camera to check for child pornography images.

"Of course I am clean, they might find some pictures of me naked, non-sexual mode photos I used once to make a birthday card for a girlfriend once, but that's about it," he wrote in an entry last August titled "Home Invasion."

His irritation with registering as a convicted sex offender and having that information publicized on a Web site maintained by the police department in his home of Fargo, N.D., was a frequent topic. He submitted anonymous questions about law enforcement's efforts to monitor sex offenders to Fargo Police Chief Chris Magnus periodically through The Forum newspaper's online "Chat with the Chief" feature and then posted the responses to his blog.

"I think it's pretty amazing you believe that as a registered sex offender your situation is comparable to being a Jew or member of another minority group persecuted by the Nazis," the police chief wrote in a May 2004 reply to Duncan's comparison of the Fargo police policy to visit the homes of high-risk sex offenders to the 1935 Nuremberg Laws (search) that stripped Jewish people of their German citizenship.

Magnus said this week his officers first learned of Duncan's blog when they questioned friends and neighbors after he failed to check in with his probation officer in May.

"Whatever questions he submitted were submitted anonymously and I certainly had no idea I was corresponding with him," Magnus said. "In retrospect now, it is a little creepy, especially after I went on his blog to read how he has this vendetta against anyone who he felt was responsible for his situation."