The mother and stepfather of Riley Ann Sawyers, who Texas authorities believe is "Baby Grace," tortured and beat the child on the day she died, according to an affidavit filed with Galveston County authorities in connection with the case.
Kimberly Ann Trenor, 19, and her 24-year-old husband, Royce Clyde Zeigler, both of Spring, Texas, are being held in connection with the 2-year-old girl's death on charges of injuring a child and tampering with evidence. The two remain in custody in Galveston County jail, each on $350,000 bond.
In the affidavit, Trenor describes how she and Zeigler beat the toddler with two leather belts and held her head under water in a bathtub on the morning of July 24. Trenor also said in the affivadit that Zeigler picked the child up by her hair and threw her across the room causing her head to slam against a tile floor.
After Sawyers died, Trenor said in the affidavit to the Sheriff's Office, Zeigler covered the child in a purple towel and the pair then went to a Wal-Mart to purchase items to hide and dispose of the body, including a blue plastic container, bleach, a shovel and latex gloves.
According to the affidavit, Trenor said Zeigler hid the container with the remains in a storage shed for two months before the pair tossed the container into the water off Galveston Causeway.
Meanwhile, Sawyers' father and grandmother publicly wept Monday as they demanded justice in the child's "heinous" death.
"It's very rough," said Robert Sawyers, who was Trenor's high school sweetheart. "I'm just so stressed out through all of this ... I keep saying that 'it's hard' would be an understatement."
Texas investigators announced on Monday that they are "fairly confident" the little girl found late last month, stuffed in a plastic box, is the missing child.
"It was a few weeks ago that I held up this shoe and asked, 'Who is Baby Grace?'" Maj. Ray Tuttoilmondo, a spokesman for the Galveston County sheriff's office, said during a news conference in which he announced the weekend arrests of the girl's mother and stepfather in connection with the little girl's disappearance and death.
The pair could face additional charges, Tuttoilmondo said, including possible murder charges.
The arrests come nearly a month after a fisherman in West Galveston Bay discovered the locked box abandoned on a small island. Inside was the body of a child who had suffered a head wound. Authorities appealed to the public for help, releasing a composite sketch of a child they called Baby Grace. Hundreds of tips from around the world poured into the Galveston County sheriff's office.
One of those involved Sawyers, a little girl who was last seen in July, when Trenor reportedly gave her to someone who presented her with custody documents that appeared legitimate, ABC News' Houston affiliate KTRK first reported last week. However, the child was never reported missing to police.
Late last week, detectives requested DNA samples from eight families with missing children resembling Baby Grace. One of the samples was submitted by Robert Sawyers, who still lives in Mentor, Ohio, the town where his daughter lived until her mother left with the girl for Texas.
The tip that Baby Grace might be Sawyers originally came from her paternal grandmother, Sheryl Sawyers, who phoned investigators after she saw the Baby Grace sketch on the Internet.
At the afternoon press conference, Sheryl Sawyers said she hoped that additional charges were filed against the pair. "I'm hoping that they are upgraded from 'injury to a child,' because she's not just injured, she's dead," Sawyers said, clutching an Elmo doll she had hoped to give to her granddaughter for Christmas if she was found.
Trenor, who was just 16 when she gave birth to the baby, had lived with the Sawyers family for two years before moving to Texas to be with Zeigler, who she reportedly met online.
"I think, pretty much, he could be anyone he wanted to be on the Internet," Sheryl Sawyers said of Zeigler. "Maybe he painted a pretty picture, and that's what made her move down there."
Tuttoilmondo said it was unclear whether Sheryl Sawyers or anyone else would be able to collect the $20,000 reward offered last week to anyone who provided authorities with information that lead to Baby Grace's identity.
When the little girl's body was found Oct. 29, investigators didn't have much to go on to identify her. They called in renowned forensic artist Lois Gibson, who came up with a sketch of the girl whom detectives called Baby Grace.
Gibson felt an overwhelming need to help determine the little girl's identity. "I needed to know the name of this girl, and I needed this to be over with," she said.
When Baby Grace was found, she was wearing a Target brand pink, flowing skirt, a pink shirt and white light-up tennis shoes with purple flowers on them. For a brief time, investigators looked into the possibility that the child's body was that of Madeleine McCann, a 4-year-old British girl, whose disappearance from a resort hotel in Portugal in May made international headlines, but they quickly ruled out a connection to that case.
It will take several weeks for DNA testing to prove conclusively that Baby Grace is Sawyers.
While Tuttoilmondo expressed thanks for the public's help in identifying the girl, and credited cooperative police work for the break in the case, he also said that tips that poured in have resulted in 22 additional missing girl cases they will continue to investigate.
The Associated Press contributed to this story.