Read it through once

“He investigated the case with great care, for Dr. Roylott’s conduct had long been notorious in the county, but he was unable to find any satisfactory cause of death. My evidence showed that the door had been fastened upon the inner side, and the windows were blocked by old-fashioned shutters with broad iron bars, which were secured every night. The walls were carefully sounded, and were shown to be quite solid all round, and the flooring was also thoroughly examined, with the same result. The chimney is wide, but is barred up by four large staples. It is certain, therefore, that my sister was quite alone when she met her end. Besides, there were no marks of any violence upon her.”