A seven-year-old boy struggled so hard as his mother drowned him that his small fists remained stiff and raised over his head hours later, the medical examiner testified Wednesday.

Noah Yates also had deep bruises consistent with someone holding him down, as did 6-month-old Mary and 5-year-old John, Dr. Luis Sanchez said at the third day of Andrea Yates' murder retrial.

Prosecutors have said they will rest their case after Sanchez testifies. During the trial's rebuttal phase, they plan to call Dr. Park Dietz, the psychiatrist whose testimony inadvertently caused Yates' conviction to be overturned.

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Dietz, also a consultant to the "Law & Order" television series, told jurors in Yates' first trial that one episode depicting a woman who drowned her kids in a bathtub and was acquitted by reason of insanity aired before the Yates children died.

No such episode existed, attorneys learned after Yates was convicted but before jurors sentenced her to life in prison.

Yates again has pleaded innocent by reason of insanity. The defense says she suffered from severe postpartum psychosis and did not know that drowning her children was wrong.

Yates is being tried only in the deaths of three of the five children, a common practice in cases of multiple slayings. The judge is not allowing prosecutors to show evidence about the injuries suffered by the other two children, 2-year-old Luke and 3-year-old Paul.

If convicted, Yates will be sentenced to life in prison because prosecutors are not seeking the death penalty. After the first jury rejected death, prosecutors could not seek execution again because they did not find any new evidence.