Kyron Horman's Father Says 'Small' Chance of Wife Being Innocent

Search for Missing Boy Kyron Horman Now a Criminal InvestigationCourtesy: Multnomah County Sheriffs Office
Pictured is Kyron Horman. Police leading the search for a 7-year-old Oregon boy who disappeared from his school 10 days ago announced today that their effort is now focused on a criminal investigation.

The father of missing Oregon second-grader Kyron Horman said there is little doubt that his estranged wife had something to do with his son's disappearance.

"I think the percentages are so small that I have no optimism in that regard, no," Kaine Horman said when asked if there was any chance his wife, Terri Horman, was innocent.

Horman, who spoke to "Good Morning America" alongside his ex-wife and Kyron's mother, Desiree Young, said Terri Horman seemed to change after the birth of their 19-month-old daughter, Kiara.

VIDEO: 7-year-olds mom and dad believe his stepmom is involved in disappearance.Play
Kyron Horman's Parents Speak Out

"She went through some post-partum depression after the birth and her emotional state was more erratic," Horman said.

Horman moved out of the couple's home with Kiara nearly two weeks ago after police reportedly told him they had evidence that Terri Horman had tried to hire the landscaper to kill him.

He has since filed for divorce and was granted an emergency restraining order keeping Terri Horman away from him and their daughter.

Though Kaine Horman, Desiree Young and Young's husband initially presented a united front with Terri Horman in the days after Kyron vanished last month, the family has now turned on Kryon's stepmother and is begging her to cooperate with police.

"I believe respondent is involved in the disappearance of my son Kyron who has been missing since June 4, 2010," Kaine Horman wrote in his application for the restraining order.

VIDEO: Why Terri Horman Called 911Play
Botched Sting Operation Complicates Search for Kyron Horman

He added, "I also recently learned that respondent attempted to hire someone to murder me. The police have provided me with probable cause to believe the above two statements are true."

Police have not named her a suspect or person of interest in the case, but Kaine Horman and Desiree Young said she failed two polygraph tests.

Terri Horman and her attorney declined to comment on the allegations made by Kyron's parents.

Young said she didn't believe Terri Horman from the beginning when she called to tell her that Kyron went missing from his elementary school.

"There was just certain details that just didn't make any sense that gave me that sick to my stomach feeling," Young said.

At a recent press conference, she implored Terri to tell the family where he is.

"Unfortunately I am kind of at that point where I am so angry I just don't even have words," she said. "I just really want her to do the right thing ... Kyron is still out there and he needs to be home."

Kaine Horman said he feels betrayed.

"I think we all do," Young added.

Young said she would hope Terri Horman would decide to give in and start talking.

"I would like to think not, because my son is involved. But I have the feeling that she will never ever give in," she said.

" I don't think she is going to tell the truth," Kaine Horman said.

"She hasn't told the truth for seven and a half years that I have known her," Young said.

Kyron Horman's Step-Mom Has "Anti-Freeze in Her Veins"

The restraining order against Terri Horman was unsealed by the circuit court in Multnomah County, Ore., Thursday after the county's Major Crimes Team told the court they no longer believed that releasing the information "would undermine their investigation into the disappearance of Kyron Horman."

The release of the restraining order came as it was revealed that a potential opportunity to arrest Terri Horman was thwarted by an ill-executed sting operation at the family's home last month.

ABC's Portland affiliate KATU is reporting that the landscaper police say Terri Horman allegedly contacted to kill Kaine Horman was in on the sting, but then raised the woman's suspicions enough that she called 911.

The landscaper showed up at Horman's door June 26 wearing a hidden microphone to demand hush money. Undercover agents were nearby. But the plan backfired when Horman called police to report an emergency, according to KATU, telling the dispatcher a man at her door wanted $10,000.

KATU cited sources as saying that was the second call of the day. The first came minutes earlier to report that someone in a truck was threatening her.

Responding officers found themselves face to face with the undercover agents and Horman was not taken into custody.

"This gal seems to have anti-freeze in her veins. I mean she's under a lot of pressure," retired Portland police captain C.W. Jensen told ABC News. "I mean the investigation, the family turning against her, the community turning against her, a divorce a separation from her child -- all these that's a lot of pressure but it seems that she has the hubris so far to push herself through."

Kaine Horman moved out of the house, taking the couple's toddler daughter with him, apparently after learning of his wife's murder-for-hire plot. It was then that a third call was placed from the Horman home that day, listed only as a custody issue. Kaine Horman filed for divorce and was granted a restraining order two days later.

"Hopefully I think the goal was to get her to talk about the case," former FBI special agent Brad Garrett told "Good Morning America." "Arrest her and that additional pressure would get her to talk."

Terri Horman has since hired a prominent defense attorney. She denied the allegation when confronted by detectives, The Oregonian reported, and she has not been charged, though the investigation is proceeding, the sources told the newspaper.

Garrett said the attempted police sting leads him to believe police think she has either direct or indirect knowledge of where Kyron is.

But, he noted, there is the chance that she's been telling the truth -- that she has no idea where her stepson may be.

"That's entirely posible," he said. "We've never heard anything from an evidence stand point that Terri knows where Kyron is."