A woman dubbed the "black widow," who is accused of murdering her husband and other partners with cyanide, is expected to plead not guilty to all charges in her upcoming trial, sources close to the matter said.

Documents submitted by lawyers for 69-year-old defendant Chisako Kakehi indicate she will likely deny the charges of murder and attempted murder-robbery involving four men, the sources said Wednesday. The papers were presented during pretrial talks at the Kyoto District Court.

A lay judge trial for the four cases will be held at the court, but the date of the first hearing has yet to be set.