The body of the offender, 24, was found headless when police raced to the apartment yesterday after an emergency call, apparently from the dying father, had been broken off in mid-sentence.
Alf Willwacher, a senior prosecutor, said an electric chainsaw was next to the son's body.
"We do not believe any third party was involved," he said.
Neighbours said the father and son had been reclusive since the death of the mother, allegedly by suicide, several years ago.
