"We know also that the revolver was fired not far from the hundred-and-fifty-foot distance; _the man was an excellent shot_, for you must consider the old style of weapon. "He must have been _large_, or at least _strong in the wrist_, for a good shot with such a weapon cannot be made by a weak person." I interrupted: "The murder of Smith was considered to be due to a pistol ball of large calibre. Could the same weapon have been used?" "It could," said Oakes. "That one has been in the family for years. The style of the cartridges is somewhat similar to our modern ones, but they are very old, as we know by their appearance. "Further," he continued, "in my opinion the 'woman story' connected with the Smith murder is based on a _man_ in a black _robe_. It may have been the same man who is at the bottom of these later mysteries--though we are to remember that when Mr. Mark was killed Joe saw no _robe_. "In the annals of crime we find very few women doing murder in that way; it is a man's method. "We must look then for a _strong-wristed_ man--a man who has also strong arms, and a _cross_ on the _left_ one; finally, a man with a knowledge of revolvers, and who has in his possession--or has had--a large, old-fashioned weapon and cartridges, and also a robe. "And one thing more strikes me," added Oakes in a slow, deliberate voice, "he is a man _with a mania_--_an insane man_--always, or at intervals." "Yes," said the doctor. "I had concluded so too, Oakes. The wearing of a robe--especially in a confined place like the wall space--the cutting out of a panel and the peculiar method of attack seem nonsensical and without proper reason. And the absence of provocation for those assaults, and for the murder of good men like Smith and Mark, point strongly to an unbalanced mind." "Probably correct," Oakes replied. "And I should say that the _insanity is present at intervals only_." "Mr. Oakes," said Chief Hallen then, "don't you think it advisable to investigate that story of the bandana handkerchief as soon as possible? Affairs in town may become pressing at any time, and we may be needed there." "Yes, Chief, certainly. We should lose no time about it," said Oakes. Then he spoke to Martin; and the latter retired and presently returned with Joe. The detective asked the boy if he would go and point out the stone from which the murderer was leaping when the handkerchief fell into the water. "You know it is nearly full moon and several of my men will go with you, and so will Mr. Martin." The negro assented reluctantly, though bravely, for he was not devoid of superstition. Oakes called in four of his men and said: "Go with Mr. Martin and Joe. Take lanterns, and find the handkerchief which is at the bottom of the stream if the boy is telling the truth, and the murderer has not recovered it. He did not notice it drop, did he, Joe?"