As early as 1714 he had to appear in court. He was flogged and branded, and convicted to 25 years in a house of correction. He soon escaped and formed a gang in the eastern part of Holland. Within a year he returned to Amsterdam, and took up residence at the Elandsgracht. Soon the numbers 71-77 were known as the 'Fort of Sjakoo'. The houses were provided with escape routes, secret passages, hidden trapdoors and box beds that could be reached by way of two separate rooms. But the houses were not a fortress as such. "Fort" was a name frequently applied to a group of houses towering above smaller neighbours.
Sjakoo was arrested again in January 1716. He managed to escape in May, but made the mistake by celebrating his regained freedom lavishly in the outskirts of Amsterdam. In the middle of his carousal he was hauled in.
His execution took place in public on the 6th of August 1718. He was decapitated in Amsterdam after having been broken on the wheel. His remains were tied to a wheel, and his head stuck on a pin in the gallows-field until they would be decayed.
The Dutch author Justus van Maurik visited the notorious part of Elandsgracht some two centuries after Sjakoo's residence there, just before the houses were to be pulled down. They had fallen into decay, not in de last place due to the persistent rumour that Sjakoo had hidden a treasure somewhere on the premises. In their desire for money the occupants had left no stone unturned. Meanwhile, after a few generations, the image had arisen of a Dutch Robin Hood, of a noble man, who only stole from the rich.
In 1886 the houses have been demolished by order of the new owner, Mr Hemker, who commissioned to build new houses for 'honest, respectable artisans'. The stone tablet at number 73 reminds us of the laying of the first stone on the 9th of June in 1886. The houses still are in possession of the Hemker family, who had always been intrigued by the curious history of the 'Fort of Sjakoo'. A lecture in the Amsterdam Historical Museum, showing Sjakoo's legacy, such as his little extension ladder (which had been especially designed for committing burglary), his pistols and crowbar, inspired them to keep the history of Sjakoo and his Fort alive by having it depicted in a memorial plaque. They contacted the sculptor and restorer Jan Hilbers and they deliberated on the depiction on the stone. Was it to be the Fort as shown on the original photograph, or Sjakoo's villain's face itself? They could not decide, and so resolved to do both.