An Overbrook woman who police say admitted punching her 3-year-old son in the stomach in anger after he messed up the bathroom has been ordered to stand trial on murder charges.

"I didn't think I hit him hard enough to do that," said Isabeth Cruz, according to Homicide Detective Joseph Bamberski, who testified Wednesday at her preliminary hearing.

Bamberski said that during her May 5 questioning, Cruz said her son, Christian Torruellas, had defecated in his pants and then went into the bathroom, where he made a mess trying to clean himself. Bamberski said Cruz, 21, told him she became angry and punched him in the stomach.

The incident happened on April 27 at her mother's house on Sparks Street in Olney.

Daniel Brown, assistant Philadelphia medical examiner, testified that three days later, on April 30, Christian became seriously ill and unresponsive, and Cruz took the boy from the Overbrook home she shared with her boyfriend to nearby Lankenau Hospital.

At Lankenau, Brown said, Christian went into cardiac arrest, was revived and stabilized, and was transferred to Children's Hospital of Philadelphia, where he died on May 3.

The Medical Examiner's Office said the cause of death was blunt-force trauma resulting from the punch.

Brown testified that the blow to the boy's abdomen had enough force to tear his small intestines in three places. Although there were also bruises around Christian's head and face and back, Brown said he found no evidence of long-standing child abuse, such as healed broken bones.

Defense attorney Walter C. Chisholm asked Municipal Court Judge Teresa Carr Deni to dismiss the murder charge against Cruz, arguing that there was no evidence of premeditation or malice in her actions against her son.

"The child defecated, it was an emotionally driven action. . . . This isn't some planned killing," Chisholm said.

Assistant District Attorney Bridget Kirn told Deni that the extent of Christian's injuries was evidence of premeditation.

"We're not just talking about his head and chin. There are eight different bruises on this child's body. That's a lot for a 3-year-old," Kirn said.

"She said she punched him. A 3-year-old who pooped himself - that happens," Kirn added.

Deni ordered Cruz held for trial on a general charge of murder, plus charges of aggravated assault, involuntary manslaughter, and child endangerment.