SAN ANTONIO -- Jurors will hear closing arguments Monday in the trial of a woman accused of drowning her boyfriend's son in 2005.

After the defense team for 28-year-old Veronica Herrera rested Thursday afternoon, the prosecution called a rebuttal witness who contradicted the defense's claim that Herrera is mentally retarded and didn't know what she was doing.

"I think in terms of knowing that the child was in distress and was being hurt, to think that she would not know that would be impossible in my mind," psychiatrist John Tennison said.

Herrera is accused of killing 3-year-old Andrew Fox by holding his head under a stream of scalding water and then taking his body to the pool at the apartment where Herrera lived with Fox's father, claiming the child had drowned in the pool.

Despite having low IQ scores, Tennison said he found several notes written by the defendant while in jail.

"When I confronted her with that and showed her this, she said, 'I can't believe you still have that,' he said. "So she was surprised to see (that) I had a copy of this document in which she had written these sentences."

If convicted, Herrera faces a maximum punishment of life imprisonment.