By Ned Randolph
SAN DIEGO, Sept 24 (Reuters) - The mother of a San Diego-area teenager who was kidnapped by a family friend last month and rescued days later in Idaho was killed by at least a dozen blows to the head and left bound and gagged inside a garage set ablaze after her death, coroners found.
Medical examiners were unable to conclusively determine the cause of death of her 8-year-old son, whose body was found burned beyond recognition in the charred ruins of an adjacent house, but they revealed he most likely died from the fire.
The two autopsy reports, issued late on Monday and posted online by a local ABC television affiliate, revealed new details in the origins of an abduction and double-murder that triggered a multi-state manhunt and drew national media attention.
The case came to public notice in early August when authorities issued a statewide child-abduction alert in California for 16-year-old Hannah Anderson and her 8-year-old brother, Ethan, both from the San Diego suburb of Lakeside.
Police launched the search after finding their mother, Christina Anderson, 44, on the night of Aug. 4 slain inside the smoldering garage owned by the suspected kidnapper, James Lee DiMaggio, with no immediate sign of her children.
The body of a child was discovered in the burned-out ruins of DiMaggio's two-story cabin next to the garage, but those remains were not positively identified as Ethan's for several days.
DiMaggio and Hannah ultimately were tracked down about a week and a half later in the Frank Church River of No Return Wilderness in Idaho, after a group of horseback riders reported to authorities that they had encountered the pair days before.
FBI agents shot and killed DiMaggio in a lakeside confrontation with the suspect and Hannah was freed unharmed.
Hannah said in comments later posted to an online chat service that she believes DiMaggio, who was a computer technician, set off the fires at his home with a timer device after taking her captive and heading to Idaho.
The high school student also said in the online comments that she, her brother and mother had been "tricked" by DiMaggio into paying a visit to his house at the outset of the ordeal.
But according to the autopsy reports, Christina Anderson had asked DiMaggio to take her 16-year-old daughter to cheerleading camp on Aug. 3 while she was attending her son's football practice. That was the last day that the mother and her son were seen alive, authorities have said.
In both autopsy reports, the San Diego County Medical Examiner ruled the deaths of Christina and Ethan Anderson as homicides. The family dog was found dead from a gunshot wound inside the garage with the mother, the coroners said.
Firefighters found the mother's body lying face down beneath a tarp in the detached garage. She had been gagged with duct tape and bound at the ankles with a plastic cable.
The coroner previously disclosed that Christina Anderson had died from blunt-force trauma to the head. The autopsy detailed numerous abrasions and lacerations to her scalp from a "minimum of 12 impact sites," but it did not identify a murder weapon.
The medical examiner also found blunt-force injuries to her extremities, as well as a gaping slash wound to her neck that appeared to have been inflicted after she died. Parts of her body also were burned.
On the boy's badly burned remains, examiners found fractures of the skull, ribs and other bones they said were most likely caused by the fire's heat but added, "traumatic causes cannot be completely ruled out."
The autopsy offered no additional clues about possible motives for DiMaggio's actions, an aspect of the case that authorities have declined to address publicly.
The children's father, Brett, who was living at the time apart from his family in Tennessee, has said he was bewildered by the actions of DiMaggio, a longtime close friend who had served as the best man at his wedding and was like an uncle to his children.
But a family friend has said the suspect developed an apparent infatuation with Hannah that made the teenager feel uncomfortable.
In yet another twist to the tragedy, a friend of the DiMaggio family came forward last month to say that the deceased kidnapper made Brett Anderson's mother, Bernice, the beneficiary of a $112,000 life insurance policy. (Reporting by Ned Randolph; Writing by Steve Gorman; Editing by Dan Whitcomb and Ken Wills)