A man who was arrested as a suspect in the disappearance of a Senath, Missouri toddler has admitted to suffocating her and disposing her body.

The details of the murder of 3-year old Breeann Rodriguez by Shawn Morgan, 43, emerged in a probable cause affidavit released to Region 8 News by the Dunklin County prosecuting attorney's office.

According to the affidavit, Morgan found Breeann standing on his pool ladder in his backyard on August 6, the day she went missing. He grabbed her, carried her inside his house, and suffocated her with a trash bag.

Morgan said it took about an hour for Breeann to die, according to the affidavit.

He put her body in the same trash bag, drove to floodway ditches off of a highway, and dumped her body over a railing. He then returned home, dismantled her bicycle, and disposed of it in the same river system.

Breeann was riding her bicycle outside of her house with her 5-year old brother the day she went missing. He went inside for a drink of water and when he came out, Breeann and her bike were gone.

A search in the area would later yield two items of interest- the training wheels of Breeann's bicycle, which were identified by her father.

In a twist to the case, Edgar Rodriguez and his wife, Claudia Ramos, both failed lie detector tests.

Rodriguez spoke with Nancy Grace about the lie detector failure.

"I don't know, honestly, honestly," he said. "When my wife went in there first to do the polygraph and she failed it, I mean, of course as a father when someone tells you they failed a polygraph, it automatically raises doubt."

He had expressed skepticism of the test and results.

"I don't know. To be completely honest with you, I don't believe we really did fail it. It may be some kind of tool they use to squeeze every bit of information out of us. I don't really know. But they said we did fail it."

Morgan is scheduled for arraignment on Tuesday for first-degree murder, armed criminal action, and tampering with evidence, CNN reported.

Morgan's motive is unknown. He lives in the same neighborhood as the Rodriguez family, but it is not clear if he had any prior connection with them, CNN reported.

Senath is a town in southeastern Missouri. It has a population of less than 2,000.