Attorney Tommy Stickler Jr. also confirmed Wednesday that the girl's mother, Kimberly Dawn Trenor, is pregnant. Her pregnancy was first reported by the Houston Chronicle.
The fatal beating happened after Royce Clyde Zeigler II stayed home from work to make sure his wife was following the discipline plan he'd established for her daughter, 2-year-old Riley Ann Sawyers, Stickler said.
Riley's father, Robert Sawyers, and grandmother, Sheryl Sawyers, appeared on CBS' The Early Show but were unable to comment on the reports that Zeigler had tortured and beaten the little girl.
Their attorney, Laura DePledge, said that they had only just heard the news and were too emotional to speak.
Riley is believed to be the girl dubbed "Baby Grace," whose body was found by a fisherman in a plastic box floating in Galveston Bay last month. The girl's identity was a mystery for weeks, and authorities are still awaiting the results of a DNA test on the body to prove she is Riley.
Police arrested Zeigler, 24, and Trenor, 19, on Saturday after Trenor told police she and her husband had killed the girl in July and hid her body in a shed before dumping it in the bay.
Neal Davis III, Zeigler's attorney, said Trenor's story isn't believable, from the information included in a chilling arrest affidavit.
"She is placing all the blame on Royce, but I think that once the facts come to light, once the timeline's established and the evidence is combed through ... I think her credibility is gonna become a big issue," Davis said.
The affidavit of Trenor's statement to Galveston authorities, released Monday, painted a disturbing picture of Riley's last days.
The girl was beaten with leather belts, had her head held underwater in a bathtub and then was thrown across a room, her head slamming into a tile floor.
An autopsy revealed that Riley suffered three skull fractures, but the cause of her death has not been determined.
Zeigler wanted his wife to spank Riley with a belt when she failed to say things like "please" and "yes sir" or "no sir," Stickler said Wednesday. Zeigler didn't believe Trenor was doing it, however, because the 2-year-old's behavior wasn't changing.
Although the affidavit said the couple abused Riley over a four- to six-hour period, Stickler said it wasn't a continuous event. Instead, Zeigler grew increasingly enraged as he spanked Riley and she kept forgetting to do things the way he wanted.
"There was never an intention to beat Riley to death," he said.
At one point, Trenor wanted to call an ambulance but Zeigler wouldn't let her, saying they'd both be arrested if officials saw her injuries, Stickler said. Instead, Riley was given some over-the-counter pain medication.
When Riley later stopped breathing, Zeigler performed CPR on her tiny body, Stickler said.
Stickler said Zeigler was overwhelmed by his sudden fatherhood and didn't know what behavior to expect from a toddler.
Trenor and Riley had moved from Mentor, Ohio, to Galveston in June to be with Zeigler after the two met playing an online game, World of Warcraft.
Robert Sawyers told The Early Show that the last time he'd seen his daughter was on May 23. While Trenor, his estranged girlfriend, had custody of Riley, Robert had visitation rights. He says that Trenor disappeared with Riley sometime in mid-June. They hired an attorney to attempt to locate the child.
On November 7, Riley's grandmother Sheryl Sawyers saw a photo on the internet.
"I saw the composite drawing of Baby Grace, and I read the story," she told The Early Show. "At that point, I did know that my granddaughter lived in Texas. The picture rather resembled her."
Sawyers says she wants people to know what kind of child Riley was.
"She loved to sing and dance and play outside," she said. "She was a wonderful little girl."
Trenor and Zeigler remained jailed Wednesday on charges of injury to a child and tampering with evidence. Bail was set at $350,000 each.