Family of 3 Slain by Arrow, Strangling : Murder: Rhode Island family had been missing since Sept. 20. Autopsies on the mother and child point to asphyxiation.

Asphyxiation appears to have caused the death of an 8-year-old girl who had disappeared with her parents, but officials may never know for sure, an investigator said last week.

The bodies of Emily Brendel, her mother, Alice, 46, and father, Ernest, 53, were found Nov. 7 in shallow graves at the edge of field in suburban Barrington, about half a mile from their home. They had been missing seven weeks.

Autopsies found that Ernest Brendel, 53, died of arrow wounds to the chest and had also been struck on the head with a blunt instrument.

Alice Brendel, 46, apparently was strangled with a piece of cloth knotted around her neck, state police Capt. Brian Andrews said.

The autopsy on their daughter was inconclusive.

“There were no visible signs of trauma, either internally or externally,” Andrews said. “You can eliminate almost everything but asphyxiation.”

Andrews said the girl’s body was found beneath her mother’s in the same shallow grave.

The Brendels were last seen on Sept. 20. Their graves were discovered by a woman walking her dog.

The chief suspect, Christopher J. Hightower, 42, was being held in state prison in lieu of $100,000 bond on charges related to the Brendels’ disappearance, but had not yet been charged with their deaths.

Hightower was arrested Sept. 23 while driving the Brendels’ car, in which were found blood, human teeth and a crossbow. He was charged with attempted extortion and illegal possession of firearms, a stolen car and credit cards.

Hightower, an investment adviser who had a soured business relationship with Brendel, also has been charged with trying to extort money from Ernest Brendel’s sister, whom he told the Brendels had been kidnaped.