Through the testimony of 14 witnesses over the last three days, prosecutors have worked to convince jurors that a 2-year-old girl died after a brutal discipline session orchestrated by her mother and stepfather.

But attorneys for Kimberly Dawn Trenor have tried to rebuff those efforts at every turn, insisting the 20-year-old never intended to kill her daughter, Riley Ann Sawyers, and the blame lies solely with her husband, who points the finger back at his wife.

"As soon as this is done I'm divorcing that pain of a wife of mine," Royce Clyde Zeigler II wrote in a letter that was shown to jurors on Thursday. He sent the letter to his half brother after being arrested. "Also the irony is they have found that my wife is a sociopath and they still hold me on that bs story of hers."

Click here for photos of 'Baby Grace.'

Click here for photos from the trial.

Prosecutors were scheduled to wrap up their case on Friday in Trenor's capital murder trial.

They contend Trenor and Zeigler are both responsible for Riley's death, saying the couple beat Riley, pushed her head in a bathtub filled with cold water and ultimately threw her across a room, fracturing her skull during a daylong discipline session on July 25, 2007, designed to teach her proper manners. Zeigler, who will be tried later, was also charged with capital murder.

In a videotaped statement to police, Trenor admitted she whipped Riley with a belt and held her head underwater but that it was Zeigler who threw the toddler across the family room.

Prosecutors Thursday showed jurors copies of suicide notes Trenor and Zeigler wrote expressing remorse.

Gabriel Watts, an FBI forensic document examiner, testified he was able to lift the impression of the suicide notes from an underlying sheet of a notebook seized from the couple's suburban Houston home.

Trenor's brief note read: "My heart is black dead. There is nothing left. I can't live with myself after Riley. I go to be."

Zeigler's note, said he was taking his life "because of guilt for past sins which I have confessed ... My wife, Kimberly Zeigler, is innocent and lived in fear because of thought of what I would do to her."

Neither Trenor nor Zeigler in their notes directly said they were responsible for Riley's death.

After Riley was killed, the couple bought a plastic container, partially filled it with cement, stuffed her beaten body inside and stored it in a shed at their home before dumping the remains 70 miles away in Galveston Bay in September 2007, according to authorities.

Watts also told jurors that Trenor and Zeigler also wrote a list of nine things that Riley needed to learn. It was discovered in a storage unit the pair rented.

The list, called "Rules for Riley," included such things as "being polite," "behaves in public," "toys stay in her room" and "listen to mom & me." There was space for a 10th item on the list but it was left blank.

Trenor and Zeigler met playing an online video game and married in June 2007 after Trenor moved with her daughter from Mentor, Ohio, a suburb of Cleveland, to Spring, a suburb north of Houston.

Riley was dubbed "Baby Grace" while investigators worked to identify her decomposed remains.

The toddler's identity was a mystery for weeks until Riley's paternal grandmother in Ohio, Sheryl Sawyers, saw an artist's sketch of the girl and told authorities in Texas she thought it was her granddaughter.

The call from Sheryl Sawyers led authorities to Zeigler and Trenor, who had invented a story that Riley had been taken away by child welfare officials in Ohio.

Trenor could receive an automatic sentence of life in prison without parole if convicted of capital murder. The jury could also convict her of a lesser charge.

Prosecutors declined to seek the death penalty against either her or Zeigler, 25, because they didn't think they could prove that the pair would be a future danger, a requirement for such a punishment.

Trenor and Zeigler are being held in the Galveston County Jail under bonds of $850,000 each.