Boise, Idaho ? Convicted sex offender Joseph Edward Duncan III 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.

Duncan was arrested Saturday at a Denny’s restaurant in Coeur d’Alene 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.

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.

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.