Defense presents case for pneumonia

The attorneys began with the most critical part of their defense: Medical testimony calling into question the prosecution case that 4-year-old Rebecca Riley died in December 2006 after her mother, Carolyn Riley, dispensed lethal amounts of psychotropic drugs. The girl, who like her two older siblings was diagnosed with bipolar and hyperactivity disorders, was on three medications before her death.

Dr. Jonathan Arden, a former chief medical examiner in Washington, D.C., and now a private consultant, testified that his review of the case shows Rebecca died of “atypical pneumonia,’’ not an overdose of drugs, specifically clonidine.

“I’m confident this is a bacterial pneumonia,’’ he said.

The case, now in its third week, is expected to go to the jury by tomorrow.

Arden said his examination of the girl’s lung tissue showed significant amounts of dead tissue near the smaller airways, suggesting that she had a powerful “necrotizing’’ pneumonia. He did not say how long she would have looked gravely ill, though he said this sickness, which he believes was caused by a mycoplasma bacteria, can become “very severe very quickly.’’

When questioned by prosecutor Heather Bradley, Arden acknowledged that Rebecca’s reported clonidine levels of 12 nanograms per milliliter were high compared to the therapeutic level of .5 to 4.5 nanograms per milliliter. But he insisted that measuring clonidine levels at death is unreliable in her case, and he believes her level was not life-threatening.

During cross-examination, Arden also disclosed that he typically charges $400 an hour for his work and $4,000-a-day for court appearances, a tab that, in this case, is picked up by the state.

Another defense witness, Robert Alan Middleberg, a forensic toxicologist from NMS Labs in Willow Grove, Penn., had testified earlier this week, appearing in the middle of the prosecution case because of scheduling issues. Middleberg said the medical examiner used a “blind needle stick’’ method of getting a clonidine blood sample from Rebecca’s leg, rather than a more careful method that requires multistep incisions.

He also said that drugs diffuse differently in a body after death, making accurate assessments difficult.

Prosecutors have argued that jurors do not have to be persuaded that only clonidine caused her death. They contend that Carolyn Riley can also be convicted of first-degree murder for her “malicious failure’’ to get medical attention for the gravely ill child. The girl’s father, Michael Riley, faces the same charge, and will be tried separately.

On behalf of the prosecution, Dr. Elizabeth Bundock, who conducted the autopsy, and Dr. Michele Burns Ewald, who specializes in poison control at Children’s Hospital in Boston, testified that Rebecca died of a lethal amount of clonidine.

Dr. Sara Vargas, a pathologist from Children’s Hospital, was a prosecution witness who partly backed up Arden’s view. She cited an aggressive pneumonia as a cause of the death, though she also cited staphylococcus or streptococcus bacteria as possible triggers.

She added, however, that both the pneumonia and toxic levels of sedating drugs acted together to kill the child. She said the drugs probably suppressed the ability of her heart and lungs to battle the pneumonia.

Beyond the medical testimony, the defense also put on Valerie Berio, the defendant’s mother, who testified that her granddaughter was well cared for and that her daughter relied on the advice of a psychiatrist, Dr. Kayoko Kifuji of Tufts Medical Center.

Through tears, she pointed to family photographs of the Riley family before Rebecca’s death. She acknowledged wondering whether Rebecca’s often-hyper behavior was simply due to “the terrible twos.’’

When asked why she never questioned Carolyn Riley about putting Rebecca on drugs, Berio answered, “I trusted her judgment.’’