Jankiel (Yankel, Yaakov, or Jacob) Wiernik (Hebrew: יעקב ויירניק; 1889–1972)[1] was a Polish-Jewish Holocaust survivor who was an influential figure in the Treblinka extermination camp resistance.

He also wrote a clandestine account of the camp's operation, A Year in Treblinka, which was copied and translated for printing in London and the US in English and Yiddish.

Wiernik grew up and lived with his family in Kobryń, Poland (then part of the Russian Empire), where he followed his father in becoming a master cabinetmaker.

[3] He lived in Warsaw and worked as a property manager at a house owned by the family of Stefan Krzywoszewski (1886-1950), a popular writer, publisher and theatre director in the Interbellum.

[4] On his arrival at Treblinka aboard the Holocaust train from Warsaw, Wiernik was selected to work as a Sonderkommando; otherwise he would have been immediately gassed and killed that day.

He was traumatized by his experiences and later wrote in his book: "It often happened that an arm or a leg fell off when we tied straps around them in order to drag the bodies away.

He wrote: "The bodies of women were used for kindling" while Germans "toasted the scene with brandy and with the choicest liqueurs, ate, caroused and had a great time warming themselves by the fire.

"[6] Wiernik described small children waiting so long in the cold for their turn in the gas chambers that "their feet froze and stuck to the icy ground" and noted one guard who would "frequently snatch a child from the woman's arms and either tear the child in half or grab it by the legs, smash its head against a wall and throw the body away.

[8] In chapter 8, he describes seeing a naked woman escape the clutches of the guards and leap over a three-metre high barbed wire fence unscathed.

When the SS recognized that Wiernik was a professional carpenter, they put him to work constructing various camp structures, including additional gas chambers.

Given the shortage of skilled construction workers accustomed to the killing process, Wiernik moved between the two divisions of the camp frequently.

He was persuaded in late 1943 to write A Year in Treblinka, in spite of his initial reluctance (Wiernik had little education and was not a skilled writer).

[3][4] After the end of World War II, Wiernik initially remained in Poland (in 1947 he testified in the trial of Ludwig Fischer).