A career criminal, Silver was involved in organized crime, specifically human trafficking and prostitution rings throughout Europe, the Americas and Southern Africa, oftentimes supported by corrupt law enforcement, becoming known as the "King of Pimps".

Anzelm, a tailor by trade, was active in petty crime, being involved in the smuggling of alcohol and tobacco, and is known to have acted in at least one robbery on a fur store, but despite being identified, he was released without punishment after the arrest.

Silver was released on 12 October 1891 and according to his own testimony, supported by police records, he ended up working as a "special agent" for NYC's Society for the Prevention of Crime [de].

In Johannesburg, he operated a network of cafes, cigar shops and police-protected brothels, with the sex workers at the latter being primarily composed of Jewish women that were trafficked from parts of Eastern Europe, steadily expanding his criminal reach within the country, including to the cities of Kimberley, Cape Town, and Bloemfontein.

He based his activities out of an establishment called the American Club, located on Sauer Street, which was described as housing "a trade union of pimps in coded, telegraphic and postal communication".

Silver continued to cooperate with police to maintain his connections and get rid of competitors, often providing anonymous testimony for criminal trials regarding burglary or theft.

[4] In 1905, Silver left for German South West Africa, setting up illegal brothels in Swakopmund and Windhoek, for which he was convicted in 1906 and sentenced to three years imprisonment, of which he served two.

Silver moved to Balvanera, Buenos Aires in 1910 and conducted human trafficking operations for his brothels in Europe within neighboring Chile, largely in the area between Santiago and Valparaíso, in addition to gun-running, while working as a police officer.

Critics note, among other things, that van Onselen provides no evidence that Silver was even in London during the months the murders took place and that the accusation is based entirely upon speculation.