Steve Groene (search), the father of two children who were allegedly kidnapped and molested by a convicted sex predator, pleaded with Americans Wednesday to protect other kids from similar fates.

"This needs to stop here," a somber Groene said in an outdoor news conference. "People like this should not be allowed in public."

Groene said Americans need to pressure lawmakers to protect children from people like Joseph Edward Duncan III (search), who is also suspected of murdering the family of the kidnapped children.

"These people are put in their positions by us, and they're supposed to be working for us, but they're not doing their jobs," Groene said of politicians as high winds blew his long, white hair across his face. He added that "people need to get on their congressmen, senators and even the president" to stop convicted predators from preying on children.

Duncan was released on $15,000 bail earlier this year after being charged with molesting a six-year-old boy in Minnesota. Prior to Duncan's arrest, police in Fargo, N.D., had been looking for him since May, when he failed to check in with a probation agent.

Describing the trauma of his ordeal, Groene said: "This is still so incomprehensible that it's going to take a long time for us to realize what's happened."

At the end of his statement, Groene seemed to choke back tears, his voice faltering. But he didn't complete the conference before reiterating the need to keep high-risk sex offenders off the streets.

"We need to get some laws changed," he said. "We need to do it quickly."

Groene's daughter Shasta, 8, is now safe in a hospital, but his son Dylan, 9, is still missing. Investigators are still trying to determine whether human remains found in a field in Montana are Dylan's.

Earlier Wednesday, police said Duncan was the sole suspect in the murder of the family and kidnapping of two children.

Shasta was recognized at a restaurant Saturday, six weeks after she and her brother vanished May 16, the same day their mother, brother and their mother's boyfriend were all found dead in the family's rural home.

Kootenai County Sheriff's Capt. Ben Wolfinger said, "We believe Joseph Duncan is the only one responsible for these crimes. There is a sense of relief ... a sense that we've got the right guy."

Duncan is set to appear in court for a preliminary hearing on July 19. He is being held on $2 million bond for charges of unlawful flight to avoid prosecution. There is no bond for the kidnapping charges he faces.

As for the remains found in Montana, Wolfinger said officials likely would not be able to conclusively identify them until next week, but they are thought to be the boy's.

Duncan was never a suspect in the attacks on the family and his name never came up until his arrest, Wolfinger said. He could not explain why Duncan's fingerprints were not found at the scene.

Wolfinger declined to say whether Duncan had a gun or to speculate on how he might have overpowered the five people at the house.

Officials still have no motive for the crimes, nor have they found a connection between Duncan and the family, Wolfinger said, raising the possibility the attack and kidnapping were random.

"When we get the pieces together, we'll find out what the motive is," he said.

Prior to his public statement, Steve Groene told FOX News' Geraldo Rivera that he has been seeing Shasta every day and spending the night with her at the hospital.

As for Duncan being the only person under suspicion, Steve Groene told FOX News that he has a "hard time believing one guy could have done all this, tied them up and all."

Earlier this week, Shasta Groene told investigators earlier this week that she and her brother were repeatedly molested by the convicted sex offender during their harrowing ordeal.

The 8-year-old's statements place Duncan inside the rural Idaho home where the girl's mother, older brother and mother's boyfriend were bound and bludgeoned to death.

“She was able to explain to the investigators in great detail the molestation,” Kootenai County Sheriff's Capt. Ben Wolfinger told FOX News.

“That was the first time she’d seen Duncan,” he said the girl stated in court documents when recounting the murders on May 16.

Shasta Groene said her nightmare began when she was awakened, tied up and carried with her 9-year-old brother to a waiting pickup truck.

Duncan, 42, of Fargo, N.D., a convicted sex offender on the run from an earlier child molestation count, was charged Tuesday in 1st District Court with two counts of first-degree kidnapping.

The intent of the crimes, court documents said, was to rape, seriously injure or commit a lewd and lascivious act on a child under 16 years old. Duncan has not been charged with anything other than the kidnapping counts, which can carry the death penalty or life in prison.

"Shasta and Dylan were repeatedly molested," Kootenai County Sheriff's Sgt. Brad Maskell wrote in a terse, handwritten affidavit released Tuesday. "Shasta saw Mr. Duncan molest Dylan."

The girl told Maskell she had never seen Duncan before.

She was awakened at her home and watched as her mother Brenda Groene, 13-year-old brother Slade and Mark McKenzie, her mother's boyfriend, were tied up, the document said. She and Dylan were also bound and placed in the pickup truck. The children were later transferred to a stolen red Jeep and taken to the first of three campsites, she said.

The affidavit does not mention the beating deaths of the girl's family or whether she witnessed the killings. It also did not say if she witnessed what happened to Dylan.

Shasta told officers that Duncan did not have an accomplice. Despite her statement, investigators were still trying to determine if Duncan acted alone, Wolfinger said.

Duncan was shackled and appeared unshaven and choked up as he quietly answered Magistrate Judge Scott Wayman's questions during a brief appearance Tuesday via video link.

Duncan had spent more than a decade in prison for sexually assaulting a 14-year-old boy at gunpoint in Tacoma, Wash., and was a fugitive at the time of his arrest after he was charged with molesting the boy in Minnesota.

Shasta and Dylan Groene's aunt, Wendy Price, told FOX News she wants the judge who released Duncan to be held accountable and she also said future cases similar to this one must be prevented.

"I believe every judge who lets these people out of jail with these low bails, slap-on-the-wrist convictions ... something has to be done. We have to start looking into the records of these judges," Price told FOX.

In his interview with FOX News, Steve Groene said he couldn't believe an "animal" like Duncan could have been released on $15,000 bail. He said he wanted to get involved in pushing through legislation that could prevent that from happening again.

FOX News' Geraldo Rivera, Jared Goldman and The Associated Press contributed to this report.