Attorneys for a Texas woman accused of drowning her five children are expected to continue calling witnesses Monday as the trial of Andrea Yates enters its second week.

On Friday, Yates' attorneys called their first witness, Dr. Melissa Ferguson, using her testimony to establish that the Houston-area woman was legally insane when she drowned her five children in the family's bathtub.

Among those expected to testify for the defense are other doctors who treated Yates in jail, family members and the family's medical expert, Dr. Phillip Resnick.

Prosecutors will be given a chance to rebut each witness. The prosecution is expected to call to the stand Dr. Park Dietz, a University of California-Los Angeles psychiatrist famous for persuading a Wisconsin jury that serial killer Jeffrey Dahmer was not insane.

On Friday, Ferguson told the court Yates was "one of the sickest patients I had ever seen" when she interviewed the mother soon after the killings.

Ferguson, a psychiatrist at the Harris County Jail, was one of the first doctors to begin treating Yates in prison.

Describing fragments of the lengthy six-day interview process, Ferguson said Yates told her, "I am Satan," and exhibited paranoia and delusions. Yates told her she felt her children were "tainted and doomed" to suffer in the fires of hell because their mother was evil.

The doctor also testified Yates had a stooped posture and a bleeding sore on her lip, and she was picking at the top of her head when Ferguson interviewed her in jail on the morning after the June 20 drownings.

At one point, Yates was agitated and "showed a lot of emotion," moaning and crying loudly, Ferguson said. She testified that Yates picked at the sore on her lip during the interview, causing it to bleed more.

Later, Ferguson said, Yates asked her for a razor so she could shave her head and reveal the "mark of the beast" — 666 — that she believed was on her scalp.

Yates, 37, is charged with two counts of capital murder in the deaths of three of the children — Noah, 7, John, 5, and Mary, 6 months. She is not on trial for the drownings of Luke, 3, and Paul, 2.

Yates confessed to drowning the children but has pleaded not guilty by reason of insanity.

Ferguson said Yates had stopped taking her anti-psychotic medication June 6, two weeks before the killings. It is unclear whether Yates ceased the regimen on her own or whether the prescription had ended.

Currently, Ferguson said, Yates is taking a cocktail of four medications: the powerful anti-psychotic medication Haldol; Cogentin, to counter the side-effects of Haldol; and the anti-depressants Effexor and Wellbutrin.

Prosecutors rested their case Friday, one day after presenting their most dramatic evidence: a videotape and photographs taken shortly after police discovered the children's bodies and an audiotaped statement that Yates gave to police.

Yates cried as parts of the silent, 15-minute video was shown to the courtroom. It showed Yates' oldest son, Noah, face down in the bathtub in a few inches of water and the other four children laid out on a bed.

Jurors also were shown photographs taken at the crime scene. Most were shown on a large, overhead screen, but some of the more graphic pictures were shown to the jury by hand so no on else could see them.

In her confession, Yates spoke in a monotone as she gave a detailed description of drowning the children. She said Noah struggled the hardest, for "maybe three minutes."

When detectives asked why she did it, she could not answer.

On the tape, she told police she had planned to kill her children for two weeks because "I realized it was time to be punished ... for not being a good mother."