A judge blocked prosecutors Friday from presenting key testimony in the trial of a Christian Science couple charged with murder for allowing their young daughter to die of diabetes without treatment.

Former banker William Hermanson, 42, and his wife Christine, 38, are charged with third-degree murder and felony child abuse in the Sept. 30, 1986, death of 7-year-old Amy. The couple sought the aid of spiritual healers but not doctors.Defense attorneys successfully blocked the testimony of a family friend who said out of the jury's presence that Amy's parents obtained medical care for themselves but didn't get Amy the insulin injections that could have saved her.