A 51-year-old woman with Lou Gehrig's disease had left a will to her father before two doctors allegedly assisted her death at her home in Kyoto last November, investigative sources said Tuesday.

The will by Yuri Hayashi, who had been developing symptoms of the progressive neurological disease since 2011, told her father that there was no need to hold a funeral for her and asked him to use her savings to deal with the aftermath of her death. It was likely prepared shortly before her assisted death, according to the sources.

The disease, also known as amyotrophic lateral sclerosis, causes gradual paralysis with no fundamental treatments established.