Walter Sartory, 73, a retired American nuclear scientist, was a savant like the character played by Dustin Hoffman in the film Rain Man and found it difficult to interact with other people.

He had shut himself away in his home in Hebron, Kentucky, where his life was dictated by intricate schedules. Mr Sartory suffered from paranoid schizophrenia and had set up a sophisticated computer system to listen for alien life.

He had also used his retirement to amass an estimated $14 million (£8.4 million) fortune on the stock market using complicated mathematical calculations.

Police and prosecutors claim his cleaning lady Willa Blanc, 48, had worked her way into his carefully protected life.

She is then alleged to have abducted him and kept him drugged and taped to a chair in her own basement for nearly a week before he died.

Miss Blanc is alleged to have put his body in a large bin and driven it to Indiana, where it was burned.

The cleaning woman, who drove a red Corvette, is alleged to have quickly spent $210,000 (£126,000) and to have been hoping to obtain another $7 million (£4.2 million).

Miss Blanc and her son Louis Wilkinson, 28, have pleaded not guilty to charges including complicity to murder, kidnapping, theft and abusing a corpse and are being held on $10 million (£6 million) bail.

Prosecutors are seeking the death penalty for Miss Blanc but have not decided whether to do so for her son.

"We all struggle to have faith in mankind," prosecutor Linda Tally Smith told the Los Angeles Times. "To think a man who was already paranoid, who lived his whole life in fear of others, could fall prey to something so horrific is heartbreaking."