Father Abrantovich was convinced that the Catholic Church in Belarus should embrace Belarusian culture and the language revival rather than continue to be a tool of colonialism and Polonization.

At the request of the Polish-speaking Hierarchy of the Catholic Church in Belarus, Abrantovich was removed from Druja and reassigned to missionary work among anti-communist Russian political refugees in Manchuria.

Abrantovich transferred to the Byzantine Rite and was promoted to Apostolic Exarch of Harbin for the Russian Greek Catholic Church.

The place and the date of his death are not established with 100% certainty, although it is thought that he died from torture in the Butyrka prison on January 2, 1946.

In 2003, the Causes for Beatification of six Soviet-era martyrs and confessors of the Russian Greek Catholic Church: Fabijan Abrantovich, Anna Abrikosova, Igor Akulov, Potapy Emelianov, Halina Jętkiewicz, and Andrzej Cikoto, were submitted to the Holy See's Congregation for the Causes of Saints by the Bishops of the Catholic Church in Russia.