In the murder trial of Amy Leanne Prien, a medical expert for the defense on Tuesday disputed the Riverside County coroner's determination that Prien's 3-month-old son died of methamphetamine intoxication.
Dr. Steven B. Karch, a cardiac pathologist who serves as a consultant for the San Francisco medical examiner, told jurors that the county's chief forensic pathologist did not adequately explore other heart-related abnormalities that could have caused the death of Jacob Wesley Smith.
"You can't look at an isolated blood value and determine it was the cause of death," Karch said. "It does not appear sufficient testing was done to rule out other causes."
Karch said the absence of DNA and other testing made it impossible for the coroner's pathologist to conclude that the baby's heart was normal.
Karch cited the possibility that Jacob could have died of sudden infant death syndrome as a result of an abnormal heartbeat pattern.
Under cross-examination by prosecutor Allison Nelson, Karch was asked if there was evidence to prove that Jacob -- whose autopsy showed levels of methamphetamine in his blood, stomach and gastric contents -- did die of a heart abnormality.
"There might have been if someone had looked for it," Karch said, but added he knew of no evidence proving an abnormality existed.
Nelson argues Prien was responsible for her son's death by allowing him to ingest the drug, possibly by breastfeeding.
But Karch dismissed the conclusion that the presence of methamphetamine in the infant's system was the likely cause of death. Karch testified that the drug typically is damaging to the hearts of adults because it contributes to a significant release of adrenalin -- an internal triggering mechanism that is not developed in infants.
"You've never seen a case where a baby died from methamphetamine abuse, is that correct?" the prosecutor asked.
"That's correct," Karch said.
The trial will continue today with Prien's attorney, Stephen Yagman, expected to call a toxicologist and Prien to testify. Yagman told Judge W. Charles Morgan on Tuesday morning that he would not call Prien to the stand, but told reporters twice outside the courtroom in the afternoon that he would.