BOISE — The father of two children murdered and another sexually assaulted by a convicted sex offender testified at the killer's federal death-penalty hearing Thursday, showing pictures of his youngest children and choking up after confirming their handwriting on notes apparently written at their kidnapper's behest.

Steven Groene said it was the first time he had seen one of the letters, which offered a false promise. "I have good news we will be home soon," it read, "maybe in a week or 2."

Joseph Edward Duncan III pleaded guilty in December to 10 federal charges in the 2005 kidnappings of Dylan and Shasta Groene, and the slaying of Dylan. A federal jury is determining whether he should be put to death or spend life in prison without parole.

Earlier, Duncan pleaded guilty in state court to murdering the children's older brother, their mother and the mother's fiance during the attack at the family's Coeur d'Alene home. Prosecutors say he killed the three to kidnap and sexually brutalize Dylan, 9, and Shasta, then 8.

As their father testified, the letters from Dylan and Shasta flashed on a screen only briefly, and prosecutors avoided discussing the contents. But they're likely to be the letters found in the car Duncan was driving just before he was arrested with Shasta in a Coeur d'Alene restaurant weeks after the kidnapping.

Excerpts suggest Duncan directed the children to write them.

"Dear dad, I miss you very much. Me and Dylan know what happened," to their slain family members, one letter from Shasta read.

"I'm sorry you had to lose a son and an ex-wife and I'm sorry we were taken from you ... We are still alive and we are ok," read another.

After testifying about the identities of his children and confirming their handwriting, Groene stepped down, visibly choked up by the evidence. Duncan, who is representing himself, did not question him.

In May 2005, Duncan went to Idaho, broke into the home and bludgeoned 13-year-old Slade Groene, his mother, Brenda Groene, and her fiance, Mark McKenzie, before abducting Shasta and Dylan and taking them to a remote campsites and other locations in Montana. After sexually traumatizing the children for weeks, Duncan killed Dylan in front of his little sister and burned his body.

Former Kootenai County Deputy Dale Moyer, now a deputy in Spokane County, Wash., was the first prosecution witness Thursday.

He knew the family from previous calls to the house, and because when the children were playing in their front yard, they would sometimes wave him down as he drove by.

"The younger girl wanted stickers," the kind featuring law enforcement insignias, Moyer said. "And the 9-year-old, he wanted to talk about guns."

On the evening of May 16, 2005, Moyer was dispatched after the sheriff's department got a call asking them to go to the house.

As he approached the front door, he noticed blood on the porch and door, Moyer said.

While waiting for the other deputies to arrive, Moyer walked around the building and looked through a window. He could hear dogs barking inside and see blood on a wall inside the home.

"There was an odor ... of carnage and carnage smells," Moyer said. "There was a definite odor."

After other deputies arrived, Moyer said he went inside, finding the three bodies and realizing that Shasta and Dylan were missing.

Duncan questioned a witness for the first time. FBI Special Agent Mike Geneckow took the stand to discuss a security video taken from a gas station in Kellogg, Idaho, on July 1, 2005, the day before Shasta was rescued.

In the video, Shasta walks around the convenience store with her arms tightly folded and Duncan nearby. At one point, Geneckow pointed out, a police car drove by the two, apparently not noticing that Shasta was the missing girl.

In cross-examination, Duncan asked the court to show the last frame of the video again — only to point out that a second police car had also passed them by.

During opening statements Wednesday, U.S. Attorney Tom Moss characterized Duncan as a cold, calculating killer and pedophile who terrorized the family because he wanted to "live out his fantasy" and exact revenge on society for perceived wrongs. Moss also said Duncan carefully researched police investigation procedures and took steps to avoid getting caught.

During his brief statement, Duncan told the jury that most of what Moss said was fair and accurate "up to the point of what occurred at the campground."

He said he would testify so he could try to "clarify things."

His standby legal counsel, Judy Clarke, has said Duncan doesn't plan to offer any mitigation, such as evidence of his own traumatic childhood.

Duncan's past is littered with arrests and prison time for crimes ranging from car theft to rape and molestation. He is suspected in the 1996 slayings of two half-sisters from Seattle and is charged with the 1997 killing of a young boy in Riverside County, Calif.

The sentencing hearing is expected to last up to six weeks.