Question

Dr. Wood, the capable general practitioner, has been requested to solve this case. He gathers information about the murder from the inmates or the house. The information is presented in two parts. 

Parts A: Background story by Arthur Conan Doyle 
Parts B: Conversation between Dr. Wood and Cecil Barker 
                                         Part A 
                                 Background Story 

The village of Birlstone is a small and very ancient cluster of half-timbered cottages on the northern border of the county of Sussex. For centuries it had remained unchanged but its picturesque appearance has attracted well-to-do residents. A number of small shops have come into being to meet the wants of the increased population. 

About half a mile from the town, standing in an old park famous for its huge beech trees, was the ancient Manor House, with its many gables and its small diamond paned windows. The only approach to the house was over a drawbridge, the chains and windlass of which had been rusted and broken. The family consisted of only two individuals - John Douglas and his wife. Douglas was cheery and genial to all and had acquired great popularity among the villagers. He appeared to have plenty of money. Thus, it came about that John Douglas had, within five years, won himself quite a reputation in Birlstone. His wife was a beautiful woman, tall, dark and slender, younger than her husband; a disparity which seemed in no way to mar the contentment of their family life. It was remarked sometimes, that the confidence between the two did not appear to be complete. There were signs sometimes of some nerve strain upon the part of Mrs. Douglas. 
Cecil Barker, was a frequent and welcome visitor at Manor House, Barker was an easy going, free handed gentleman. 
It was on Jan 6th at 11:45 that the alarm reached the small local police station that John Douglas had been murdered. Dr. Wood seemed to be unnerved and troubled. 

                                       Part B 
Conversation between Dr. Wood and Cecil Barker

Dr. Wood : We will touch nothing until my superiors arrive. {He spoke in a hushed voice, stating at the dreadful head) 
C.Barker : Nothing has been touched untilnow. 
Dr. Wood : When did this happen? 
C.Barker : It was just half-past eleven. I was sitting by the fire in my bedroom when I heard the gun shot. In thirty seconds I was in the room. 
Dr. Wood : Wasthedooropen? 
C.Barker : Yes, it was open. Poor Douglas was lying as you see him. 
Dr. Wood : Did you see anyone? 
C. Barker : No, I heard Mrs. Douglas coming down the stains behind me, and I rushed out 1 to prevent her from seeing this dreadful sight. 
Dr. Wood : But I have heard that the drawbridge is kept up all night. 
C. Barker : Yee,it was up until l lowered it. 
Dr. Wood : Then how could any murderer have got away? It ls out of question! Mr Douglas must have shot himself. 
C. Barker : That was our first idea. But see! The diamond paned window is open to its full extent. 
Dr. Wood : I think someone stood there while trying to get out. 
C. Barker : You mean that someone waded across the moat? 
Dr. Wood : Exactly!
C. Barker : I agree with you. 
Dr. Wood : But what I ask you ls, how did he even get into the house at all if the bridge was up? 
C. Barker : Ah, that's the question. 
Dr. Wood : At what time was the bridge raised? 
C. Barker : It was nearly 6 O'clock. 
Dr. Wood : Then it comes to this, if anyone came from outside -if they did-they must have got in across the bridge before six and had been in hiding ever since. The man was waiting. He shot him, when he got the chance. 

Answer 1

Part A
Background Story
The background story gives a picturisation of the location of the story. This also gives an account of how Mr. Douglas became popular in Birlstone.
Part B is a discussion between Dr. Wood, and Mr. Barker at the crime scene. Certain things raise suspicion in Dr. Wood’s mind. The drawbridge was open in the night. The door was open and the window pane was broken. Mr. Douglas was in another room.