Why was there a possibility of Mrs. Douglas and Baker being the murderers? Write in 30-40 words with textual evidence.

Mrs. Douglas and Bark seem very close.... she does not appear to be the grieving widow. Barker's They slipper is stained with blood, and Douglas' ring was removed after the murder. Holmes determined that the bicycle belonged to an American, and he notes that the murder was committed half an hour before they were informed. It is also determined that Mrs. Douglas and barker arrived at Birlstone house before the murderer escaped, and that they also helped him to escape.