Miklós was born the only child of Imre Fleischer and Katalin Krausz, and lived with his parents in Tét. In May 1944, the members of the small community in Győr County were deported to the ghetto of Győrsziget, and from there to the Budai út collection camp on the outskirts of Győr. The freight train carrying Jews from Győr and the surrounding area arrived at the Birkenau ramp on 17 June. Barely 400 men and women were selected for work. The rest were immediately sent to the gas chambers, including Miklós and his mother. His father, Imre Fleischer was selected for work. On 19 June 1944, he was taken by a transport of Hungarian prisoners to the Mauthausen camp complex, where he was employed at an outside workplace (Aussenkommando Quarz) in the Melk subcamp. According to an SS report he allegedly committed suicide on 26 August 1944, but most probably he was murdered.