vera maresova , 50 , has confessed to killing five women and one man over a four-year period at a hospital in rumburk - a small town in the north of the country .
dubbed ` nurse death ' by local media , maresova injected the potassium straight into the blood stream of her six elderly patients , which caused them to suffer heart failure and eventually death .
all of her victims were already in the intensive care unit at the hospital and it is believed maresova thought their deaths would simply be attributed to natural causes that