Oops! There goes the insanity defense.

Convicted sex offender Joseph Edward Duncan bragged to his 8-year-old captive during more than six weeks on the run, telling her how he used a shotgun and hammer to kill her family after staking out their home for days, court documents show.

Shasta Groene remembered it all and has been providing authorities with details that are building a strong case against Duncan.

Duncan was charged Tuesday with three counts of first-degree murder and three counts of first-degree kidnapping in the deaths of Shasta's mother Brenda Groene, 40, her brother Slade, 13, and Groene's boyfriend Mark McKenzie, 37. If convicted, he could face the death penalty.

"He told her he was out driving around looking for children to kidnap," Kootenai County sheriff's detective Brad Maskell testified during a probable cause hearing. "He ... saw her playing in the yard with her brother and wearing a bathing suit. At that point he chose them as possible kidnap victims."

Public defender John Adams declined to comment after the hearing. "We try to do our litigation in the courtroom," he said.

Shasta's ordeal began when she heard her mother call her into the living room early on the morning of May 16. Her mother, brother and McKenzie were bound with zip-ties and duct tape.

Duncan then bound her and Dylan and left them on the ground outside near a swing set. Shasta said she heard McKenzie yell out several times, and at one point they saw Slade stagger, incoherent and bleeding profusely from the head, out of the home. The children yelled for Slade to untie them, but he was unable to respond.

Shasta remembered that Duncan wore dark gloves and had a shotgun and night-vision goggles. She also recalled the brand name of the hammer used to bludgeon the victims, which Duncan showed her after the attacks.
During weeks of captivity at a remote campsite in western Montana, Duncan told Shasta that he cased the family's home for two to three days, using his goggles to look in the windows and study the family's habits and the layout.
(Thanks to AP and Yahoo!News.)