that night in london the chief of the criminal investigation department sat in his office. it required ten minutes to midnight, and he had just laid down his pen after several hours’ hard work over official correspondence and reports.

the goldberg case was still exercising the public mind, and several editors were asking the world from editorial easy chairs what the police were paid for.

the night was warm, and through the open window came vague and fugitive sounds from the city that never sleeps; voices, the bells of passing hansoms and the clop, clop of the horses’ hoofs, the hum of distant traffic.

a little draught of wind suddenly stirred the papers on the desk before him; he turned, the door was open, and freyberger stood before him, pale, haggard and bearing a black bag in his hand. behind freyberger stood a stranger.

“i knocked, sir,” said freyberger.

“ah! i was thinking. i suppose i did not hear you. sit down—this gentleman——?”

“this gentleman’s name is hellier, sir,” replied freyberger. “i have ventured to bring him with me as he has assisted me in clearing up the gyde case.”

“ah! what’s that you say?”

“the gyde case, sir. also he has saved my life to-day—”

“sit down, sit down,” said the chief, indicating chairs. “this is good, if it is as you say. i want details; but first tell me, is sir anthony gyde alive?”

“no, sir, he was murdered in the cottage on the fells.”

“good god! by whom?”

“klein.”

“is klein alive?”

“no, sir, he is dead. he died to-day, and his body lies in the mortuary at reading. let me say at once, and with the humility of a man who has just escaped a terrible death, that all my assumptions were absolutely correct. klein, alias kolbecker, alias müller, was the author of the lefarge tragedy, the gyde tragedy and all the subsidiary murders, concluding with the murder of bronson yesterday. look at this.”

he produced a black notebook from his pocket. the chief examined the book; it was a volume of some hundred pages or so, every page covered with close writing.

“this book,” said freyberger, taking back the volume, “contains the life history of the greatest criminal who ever lived. it is the diary of ludwig spahn, alias müller, alias kolbecker, alias klein. i mastered it in the train to-night, and from it i will sketch you the story of which the murder of sir anthony gyde is but a chapter.

“spahn was born in munich, sixty-five years ago.”

“sixty-five?”

“yes, sir. he was an old man.”

“but the man in the photograph was a man of middle age.”

“yes, sir. he seemed of middle age, but i will explain the matter as i go on. spahn, at seventeen, left the business to which he was apprenticed and went to rome to study art, or, to speak more correctly, to teach it, for this strange genius had ideals of his own, and very soon he had a little following, a cult. vicious to the core, he never could keep money. he was always in debt. one day he murdered a banker, was caught red-handed, sentenced to death and allowed to escape the extreme penalty by that infernal law which allows murderers to escape unexterminated. he was condemned to imprisonment for life and released after twenty-five years.

“he was fifty when he left prison, full of hatred towards society and a determination to be revenged.

“he went to paris.

“the art which was born with him remained with him, and the love of pleasure.

“he refused to be old, and, with the aid of the art of the chemist and the maker-up, he appeared to the world as a man at least twenty years younger than he was.

“he lived for years in paris in the latin quarter, a notoriously vicious character, yet forgiven for the sake of his genius. his sculptures were marvellous, but his vice and laziness were to match, so he made little profit of his art and did little work.

“his hatred of the rich and well-to-do amounted to a monomania, and he was always searching around for some means by which he might avenge himself upon them.

“to the man who hates a class, an individual of that class will serve as a butt for his revenge.

“one day, walking along a street in paris, he saw coming towards him what seemed a little old man wearing a pinafore. it was a child wearing a mask.

“the occurrence gave him food for thought. ‘if,’ said he to himself, ‘a man who makes these paper masks for five sous a dozen, can produce an even momentary illusion, what could not a genius do in the same direction were he to give all his mind to the matter?’

“he played with the subject in his mind.

“‘if i wanted to make the mask of a man,’ thought he, ‘a mask that would deceive everybody by its resemblance to the flesh, how would i proceed?

“‘i would first have to procure a cast of his face, or execute a bust of him exactly identical with the reality. only very slightly larger.

“‘i would then rub that face of marble with a very fine powder, and i would apply a coating of the finest caoutchouc, over that a layer of stiffening varnish.

“‘i would remove the whole, and paint the interior of the caoutchouc with the flesh tints, thus giving the true appearance of life, for the human face is painted from the inside.

“‘i would then back the thing with a thicker layer of rubber and remove the stiffening varnish from the outside.

“‘if my art did not fail me, i would now have a facsimile of my friend or my enemy’s face. could i wear it and masquerade as him? only on two conditions (1) that i could make the inside of the mask a perfect mould of my own face (2) that he was a man, a man of my own height and a man who wore glasses and a beard, for the joining at the eyes and at the neck would present an insuperable difficulty were i to imitate a clean-shaven man who did not wear glasses.’

“he brooded over the thing.

“one day he fell in with m. lefarge, a rich jeweller, who was at times a frequenter of the latin quarter, and the whole diabolical plan of the lefarge case was conceived in a flash.

“the plan of robbing and murdering a rich man in such a manner that the world would fancy that the rich man was the assassin, not the victim.

“he made a bust of lefarge, from the bust he made lefarge’s face. lefarge wore a beard and glasses. the making of the exterior of the mask was a bagatelle; the real difficulty was the interior, which had to be a perfect adaptation to his own features, but he did it.

“whilst this was going on, he made a most profound study of lefarge himself: his walk, his manner, his voice, his handwriting.

“he was, in fact, preparing to be lefarge’s understudy for an hour or two upon the stage of life.

“for three hours every day, during a space of four months, he wore the mask, conversing with himself, laughing and talking before a looking-glass, so that the thing might gain the lines and wrinkles of life.

“one day he asked lefarge to call upon him.

“lefarge called. muller murdered him, and stripped him of his clothes and decapitated him.

“then he dressed the body in his own clothes, put on the clothes of his victim, put on his face, put on his hat, his manner, his walk and his voice.

“then, with his victim’s head in a black bag, he ran down the stairs, got into his victim’s carriage, drove home, collected a hundred thousand pounds’ worth of jewels, drove to the corner of the rue d’amsterdam and disappeared.

“but nemesis followed him. the murder of lefarge had wakened up the lust for killing that lay like a spectre in the darkness of his soul. he killed three people to satiate this madness, as we have seen. then he was at peace.

“six years passed. then, in vienna, he met sir anthony gyde.

“he was living in vienna under the name of klein; living extravagantly on the proceeds of the lefarge business. he belonged to a very vicious circle, amidst whom gyde became implicated, and he was in low water financially.

“klein looked at gyde, and saw that here was another chance of playing the old comedy of masks and faces. for gyde’s face and figure lent themselves entirely to the trick.

“he obtained a hold over gyde and blackmailed him to a considerable amount, but this did not satisfy him.

“his hatred of the rich and well-to-do and respected had to be satiated.

“he made a bust of gyde and his face, he studied him profoundly. he could reproduce his handwriting with absolute and marvellous precision, and his voice.

“the bust was made in london; he took rooms in howland street, broke up the bust and came to cumberland.

“took the cottage on the fells and awaited the coming of sir anthony.

“sir anthony called upon him, as we have seen.

“klein stunned him with a sandbag, stripped him and decapitated him; dipped the head in a solution of chlorine which shrunk the skin and preserved it, placed the head in a black leather bag, dressed himself in his victim’s clothes, assumed his face and personality, dressed his victim in his own clothes and departed.

“we know the rest. but one or two points may be made clearer.

“on his arrival in london the supposed gyde went to his bedroom. there was one weak point about the mask. its prolonged use caused insufferable torment to the wearer, on account of the skin irritation it caused.

“he had removed the mask for a moment when leloir, who had left the room, returned, and saw reflected in a looking-glass his master removing his own face. klein, hearing the footstep of leloir, turned.

“the expression on klein’s face at that moment is preserved for us in the retinal photograph taken from the eye of the valet, who, beholding this monstrosity, gave vent to the awful cry heard by the secretary and fell dead.

“klein, in his hurry and the confusion caused by this incident, collected all the jewellery he could find. having no immediate plan he thought it safest to leave his victim’s head behind him, trusting it would not be discovered for some time. he passed the night at howland street, going there disguised as gyde. next morning, early, under the same disguise, he withdrew the jewels at the bank and cashed the cheque at the jewellers. it was a cheque he had found in the pocket of his victim, and he cashed it, not so much for the money as to foul his traces and prove to the police, by extra evidence, the existence of gyde.

“then he destroyed the mask and became klein again, taking the house in st ann’s road, and moving in there with a few sticks of furniture hastily bought.

“mr goldberg’s murder followed.

“then this gentleman, mr hellier, saw him and followed him. and klein suspected that he was at last suspected.

“he determined to disguise himself. how? simply by becoming his own age.

“he flung away all artifice, and became the old man he was. the removal of his false teeth alone gave him twenty years of age.

“he took the cottage at sonning, determining to lie close. but the murder instinct was too strong for him, and he killed bronson.”

then freyberger told his own story.

“i was lying in the cottage listening to this monster digging my grave, when, suddenly, i heard him fall crash amidst the weeds. i fainted, i believe. mr hellier will tell you the rest.”

“i had a reason for mixing myself up in this affair,” said hellier; “and, reading of the murder of bronson i came down to sonning to make inquiries. i asked, had anyone come to live there lately? and i was told by a woman that a gentleman had taken a cottage on the henley road. fortunately, she did not say an old gentleman, or i should not have gone there.

“i went to the cottage, knocked, could get no answer, and went round the backway.

“in the back garden, by a newly-dug grave, i found a man lying, with a spade clutched in his hand; he was dead. i found mr freyberger bound in the cottage, and i released him.”

“klein must have dropped dead then?” said the chief.

“yes,” replied freyberger. “he died of heart-disease, accelerated by the excitement of digging my grave.”

“one last question,” said the chief, “how about those initials tattooed on the body of gyde?”

“they were tattooed after death,” replied freyberger, “and as a blind. he had the art of tattooing post mortem and, strangely enough, it was this piece of cleverness that connected the cases in my mind and gave us our man.”

as hellier left the yard that night, somebody, who had followed him, touched him upon his shoulder. it was freyberger.

“i want to tell you,” he said, “just this. if you hadn’t mixed up in the affair and scented out those subsidiary murders i wouldn’t have caught klein.”

“you mean,” said hellier, laughing, “klein would not have caught you.”

“yes, that is the better way of putting it, for klein was the real hero of this business; and if all criminals were made like klein—”

“why, then,” said hellier, “society would be lost, unless all detectives were made like freyberger.”