TYLER, Texas  —  The husband of a woman who smashed her sons' skulls with rocks testified Tuesday that he saw no change in his wife's mood before the attack and no clue that she was capable of killing the boys.

"I don't understand it," said Keith Laney, who has stood by his wife in court.

Deanna Laney (search), a deeply religious stay-at-home mother who home-schooled (search) her children, has pleaded innocent by reason of insanity to charges of murder and causing serious injury to a child. She has said God told her to kill her children.

Keith Laney (search), 47, smiled at his wife when prosecutors asked what year they were married, but briefly lost his composure at the sight of a poster-sized photograph of the three smiling boys, taken months before the killings.

The jury on Tuesday also saw a crime-scene video of 8-year-old Joshua and 6-year-old Luke, lying dead in a yard, near garden signs that read, "Mom's Love Grows Here" and "Thank God for Mothers." The boys were found in their underwear with heavy rocks on their chests.

The video also showed a large spot of blood in a baby bed, where Deanna Laney severely injured the couple's youngest son, Aaron, 14 months old at the time.

Laney, 39, lowered her head during the testimony and wept as graphic autopsy photos were shown to the jury of eight men and four women.

To show the severity of the attack on Joshua, prosecutor Matt Bingham hammered a 16-pound rock into the floor of the courtroom eight times. Vibrations were felt throughout the courthouse.

Prosecutors contend that Laney knew right from wrong when she killed her children last Mother's Day weekend in the little town of New Chapel Hill (search), 100 miles southeast of Dallas.

But two psychiatric experts for the defense, two for the prosecution and one for the judge all have said Laney was insane according to the legal definition.

Prosecutors are not seeking the death penalty.