Karl Hoffman was born in Russia. He moved to London where he associated with a group of Russian revolutionaries that included Peter Piaktow (Peter the Painter), Yakov Peters, George Gardstein, Fritz Svaars, Max Smoller, John Rosen and William Sokolow. Hoffman rented a room at 36 Lindley Street.
On 21st November, 1910, Smoller, using the name, Joe Levi, he asked to rent a house, 11 Exchange Buildings. His rent was ten shillings a week, and he took possession on 2nd December. Fritz Svaars rented 9 Exchange Buildings on 12th December. He told the landlord that he wanted it for two or three weeks to store Christmas goods and paid five shillings deposit. Another friend, George Gardstein, borrowed money so that he could buy a quantity of chemicals, a a book on brazing metals and cutting metals with acid.
On 16th December 1910, a gang that is believed to included Smoller, Svaars, Gardstein, Hoffman, Peter Piaktow (Peter the Painter), Yakov Peters, Yourka Dubof, John Rosen and William Sokolow, attempted to break into the rear of Henry Harris's jeweller's shop in Houndsditch, from Exchange Buildings in the cul-de-sac behind. The Daily Telegraph reported: "Some two or three weeks ago this particular house in Exchange Buildings was rented and there went to live there two men and a woman. They were little known by neighbours, and kept very quiet, as if, indeed, to escape observation. They are said to have been foreigners in appearance, and the whole neighbourhood of Houndsditch containing a great number of aliens, and removal being not infrequent, the arrival of this new household created no comment. The police, however, evidently had some cause to suspect their intentions. The neighbourhood is always well patrolled. Shortly before 11.30 last night there were sounds either at the back of these newcomers' premises or at Mr Harris's shop that attracted the attention of the police."
A neighbouring shopkeeper, Max Weil, heard their hammering, informed the City of London Police, and nine unarmed officers arrived at the house. Sergeant Robert Bentley knocked on the door of 11 Exchange Buildings. The door was open by Gardstein and Bentley asked him: "Have you been working or knocking about inside?" Bentley did not answer him and withdrew inside the room. Bentley gently pushed open the door, and was followed by Sergeant Bryant. Constable Arthur Strongman was waiting outside. "The door was opened by some person whom I did not see. Police Sergeant Bentley appeared to have a conversation with the person, and the door was then partly closed, shortly afterwards Bentley pushed the door open and entered."
According to Donald Rumbelow, the author of The Siege of Sidney Street (1973): "Bentley stepped further into the room. As he did so the back door was flung open and a man, mistakenly identified as Gardstein, walked rapidly into the room. He was holding a pistol which he fired as he advanced with the barrel pointing towards the unarmed Bentley. As he opened fire so did the man on the stairs. The shot fired from the stairs went through the rim of Bentley's helmet, across his face and out through the shutter behind him... His first shot hit Bentley in the shoulder and the second went through his neck almost severing his spinal cord. Bentley staggered back against the half-open door and collapsed backwards over the doorstep so that he was lying half in and half out of the house."
Sergeant Bryant later recalled: "Immediately I saw a man coming from the back door of the room between Bentley and the table. On 6 January I went to the City of London Mortuary and there saw a dead body and I recognised the man. I noticed he had a pistol in his hand, and at once commenced to fire towards Bentley's right shoulder. He was just in the room. The shots were fired very rapidly. I distinctly heard 3 or 4. I at once put up my hands and I felt my left hand fall and I fell out on to the footway. Immediately the man commenced to fire Bentley staggered back against the door post of the opening into the room. The appearance of the pistol struck me as being a long one. I think I should know a similar one again if I saw it. Only one barrel, and it seemed to me to be a black one. I next remember getting up and staggered along by the wall for a few yards until I recovered myself. I was going away from Cutler Street. I must have been dazed as I have a very faint recollection of what happened then."
Constable Ernest Woodhams ran to help Bentley and Bryant. He was immediately shot by one of the gunman. The Mauser bullet shattered his thigh bone and he fell unconscious to the ground. Two men with guns came from inside the house. Strongman later recalled: "A man aged about 30, height 5 ft 6 or 7, pale thin face, dark curly hair and dark moustache, dress dark jacket suit, no hat, who pointed the revolver in the direction of Sergeant Tucker and myself, firing rapidly. Strongman was shot in the arm, but Sergeant Charles Tucker was shot twice, once in the hip and once in the heart. He died almost instantly.
As George Gardstein left the house he was tackled by Constable Walter Choat who grabbed him by the wrist and fought him for possession of his gun. Gardstein pulled the trigger repeatedly and the bullets entered his left leg. Choat, who was a big, muscular man, 6 feet 4 inches tall, managed to hold onto Gardstein. Other members of the gang rushed to his Gardstein's assistance and turned their guns on Choat and he was shot five more times. One of these bullets hit Gardstein in the back. The men pulled Choat from Gardstein and carried him from the scene of the crime.
Yakov Peters, Yourka Dubof, Peter Piaktow and Fritz Svaars, half dragged and half carried Gardstein along Cutler Street. Isaac Levy, a tobacconist, nearly collided with them. Peters and Dubof lifted their guns and pointed them at Levy's face and so he let them pass. For the next half-hour they were able to drag the badly wounded man through the East End back streets to 59 Grove Street. Max Smoller and Nina Vassilleva, went to a doctor who they thought might help. He refused and threatened to tell the police.
They eventually persuaded Dr. John Scanlon, to treat Gardstein. He discovered that Gardstein had a bullet lodged in the front of the chest. Scanlon asked Gardstein what had happened. He claimed that he had been shot by accident by a friend. However, he refused to be taken to hospital and so Scanlon, after giving him some medicine to deaden the pain and receiving his fee of ten shillings, he left, promising to return later. Despite being nursed by Sara Trassjonsky, Gardstein died later that night.
The following day Dr. Scanlon told the police about treating Gardstein for gun-shot wounds. Detective Inspector Frederick Wensley and Detective Sergeant Benjamin Leeson arrived to find Trassjonsky burning documents. Soon afterwards, a Daily Chronicle journalist arrived: "The room itself is about ten feet by nine, and about seven feet high. A gaudy paper decorates the walls and two or three cheap theatrical prints are pinned up. A narrow iron bedstead painted green, with a peculiarly shaped head and foot faces the door. On the bedstead was a torn and dirty woollen mattress, a quantity of blood-stained clothing, a blood-stained pillow and several towels also saturated with blood. Under the window stood a string sewing machine, and a rickety table, covered with a piece of mole cloth, occupied the centre of the room. On it stood a cup and plate, a broken glass, a knife and fork, and a couple of bottles and a medicine bottle. Strangely contrasting with the dirt and squalor, a painted wooden sword lay on the table, and another, to which was attached a belt of silver paper, lay on a broken desk supported on a stool. On the mantelpiece and on a cheap whatnot stood tawdry ornaments. In an open cupboard beside the fireplace were a few more pieces of crockery, a tin or two, and a small piece of bread. A mean and torn blind and a strip of curtain protected the window, and a roll of surgeon's lint on the desk. The floor was bare and dirty, and, like the fireplace, littered with burnt matches and cigarette ends - altogether a dismal and wretched place to which the wounded desperado had been carried to die." Another journalist described the dead man "as handsome as Adonis - a very beautiful corpse."
John Rosen went to visit Nina Vassilleva on the 18th December, 1910. She asked him "have you brought trouble". He gave a slight shrug and said "I don't know". Nina refused to let him in and he left the building. Rosen went into hiding but in early January 1911 he told his girlfriend, Rose Campbell, that he had been involved with the Peter the Painter gang. She in turn confided in her mother, who told her son-in-law Edward Humphreys, who went to the police. Rose denied the story and on 31st January, she married Rosen.
Rosen was arrested on 2nd February. His first words were "I know you have come to arrest me." Rosen admitted visiting 59 Grove Street on the day of the murders but said that he had spent the evening with Karl Hoffman at the pictures, and later in his room, before going home. The following day he met Hoffman again but he said he knew nothing about the murders. However, Rosen did tell the police "I could show you where a man and a woman live, or were living, who are concerned in it, but I don't know if they have moved since I have been here."
On 15th February, 1911, Karl Hoffman was charged with conspiracy to break and enter into the Henry Harris's jeweller's shop. When questioned he refused to admit that he knew George Gardstein, Peter Piaktow (Peter the Painter), Yakov Peters, Max Smoller, Fritz Svaars, Yourka Dubof, John Rosen and William Sokolow. Hoffman claimed that on 16th December he had gone to bed at midnight and nobody had visited his room. The only witnesses against Hoffman were Nicholas Tomacoff and the landlady at 35 Newcastle Place, who both seen him, on separate occasions, in Svaars' lodgings.
Theodore Janson, a Russian immigrant and a police informer, claimed that he had asked Hoffman on Christmas Day if Peters and Dubof, who had been arrested, were guilty of the murders. Hoffman had apparently laughed and replied: "No, there were nine men in the plot, none of them are yet arrested. It's a pity the man is dead (meaning George Gardstein), he was the ablest of the lot and leader of the gang. He also managed it that some members of the gang didn't know the others."
The trial of the Houndsditch murders opened at the Old Bailey on 1st May. Yakov Peters and Yourka Dubof were charged with murder. Hoffman, Peters, Dubof, Max Smoller and John Rosen were charged with attempting to rob Henry Harris's jeweller's shop. Sara Trassjonsky and Nina Vassilleva, were charged with harbouring a felon guilty of murder.
The opening speech of A. H. Bodkin lasted two and a quarter hours. He argued that George Gardstein killed Robert Bentley, Charles Tucker and Walter Choat and Smoller shot Gardstein by mistake. Justice William Grantham was unimpressed with the evidence presented and directed the jury to say that the two men, against whom there was no evidence of shooting, were not guilty of murder. Grantham added that he believed that the policeman were killed by George Gardstein, Fritz Svaars and William Sokolow. "There were three men firing shots and I think they are dead."
The prosecution's principal witness that linked Peters and Dubof to Gardstein was Isaac Levy, who saw the men drag him along Cutler Street. Levy came under a fierce attack from defence counsel. After his testimony, Justice Grantham said that if there was no other evidence of identification he could not allow any jury to find a verdict of guilty on Levy's uncorroborated statement. After Grantham's summing-up made it clear that none of the men should be convicted of breaking and entering, the jury found them all not guilty and they were set free.
Hoffman thought that the Barber was trying to save his own neck at the expense of the others. His own view was that there was no point in confessing as the police were looking for twenty-eight people - they believed this to be the size of the group - and wouldn't call off the hunt for the others. The Prison Governor questioned him about the note but Hoffman said it was only a friendly message and denied knowing Dubof before his arrest. He persisted in his denial even when the Governor produced Dubof's note suggesting that they should say that they had only known one another since March or April 1910, when Dubof was living at Wellesley Street. From April to September, the note continued, Dubof had been in Switzerland but they had kept in touch and afterwards met intermittently when they were both looking for jobs. They had gone to Grove Street on 16 December to discuss the decorations for the Lettish concert. Dubof was worried because he had told his lawyer that he had gone to Hoffman's lodgings on 18 December, but if possible he didn't want this mentioned although he had been seen there on that occasion by Hoffman's landlord and landlady; if they didn't mention this in their evidence neither would he. Since then, they were to say, they hadn't met. Dubof wasn't sure whether it was wise to make a confession or not; he would ask his lawyer if it meant a lighter sentence. Until then he advised against it. There was no point in making trouble unnecessarily. It was best to wait and see. They must continue to stress that they were just ordinary working men and casual acquaintances.