Circumstantial evidence can be powerful evidence, but it is important you examine it carefully and consider whether the evidence upon which the Crown relies in proof of its case is reliable, whether it does indeed prove guilt. Furthermore before convicting on circumstantial evidence, you should consider whether it reveals perhaps other circumstances which may be of sufficient reliability and strength to weaken or destroy the case that is presented.
Finally it is very important for you to distinguish between arriving at conclusions based on reliable evidence that you accept and mere speculation on the other hand. Speculation is just a smart word for guesswork, and that is not a permissible activity in any court of law.
There is another important feature upon which I must direct your attention. Remember what I said only a minute or two ago about the burden of proving guilt always being on the prosecution and that you may only convict if you are sure of guilt. We are of course concerned with events which took place a very long time ago. Mrs. Park died in 1976, over 28 years ago. You must appreciate that there is a real danger of prejudice to a defendant, and the possibility must be in your mind when you decide whether or not the prosecution have made you sure of guilt. You will of course make allowance for the fact that the passage of periods of time even shorter than those with which we are considering, memories can fade. Witnesses, whoever they may be, cannot be expected to remember with crystal clarity events which occurred many many years ago. Sometimes the passage of time plays tricks on the memory. For example, Mr. Shaw who saw the incident with Mrs. Walmsley where Mrs. Park went berserk or lost it. He was inclined to say it was in April of 1976. We all know, Members of the Jury, I suspect that he is wrong about that. It was the year previously. An example of memories tricking, tricks played on the memory with the passage of time.