Murder mystery

Sarah raised her eyes to the third floor window once more.The nice old lady who waved to her every morning hadn't been seen for days.
On friday, she had served tea while Sarah busied herself with old photographs.The old lady had smiled conspiratorially and whispered:
''I've made my will, Dear. Everything is for you, you've always been so kind, unlike my good for nothing relatives.''
Today at last, Sarah had called 999. When the paramedics broke down the door, she already knew what they would find. A sweet old lady apparently dead of a heart attack while sipping her tea.