Tzvi was born on July 17, 1914 in Warsaw, capital of Poland, to Freida Leah and Shimon Yosef Miller. His father was a sewing-machine technician. His mother was a homemaker.

His family was Religion Zionist, so when they decided to make aliyah, they consulted their local rabbi, who naturally approved. This was in 1924.

In the Land of Israel, the father continued in his profession, while the mother opened a poultry store. Tzvi studied in yeshiva in Jerusalem. There he joined Beitar, and eventually Irgun Bet (i.e. IZL).

In 1935, he married Hannah Wagman, and they had two children.

In 1941, he joined Lehi in Jerusalem because it matched his ideology and outlook. He did not tell his family. Tzvi was unusual, as he was married with two children, while most Lehi members were single and young.

From Jerusalem, he moved with the family to Nes Ziona, working in the intelligence division of the underground there and in Rehovot. He also acquired weapons.

In 1948, as the State was established, he enlisted in the IDF, serving in the Infantry Corps as a corporal; he was discharged in 1950 at the end of the War of Independence. He served in the reserves until age 55. He fought in the Sinai War, and he was in charge of Camp Rafiah, maintaining order, organization and supplies.

After his demobilization, he worked as a sign-painter. His hobby was painting as well. His art went on to be exhibited at the Lehi Museum.

Tzvi was dedicated to his family and his homeland, a diligent worker and loyal frien