Zvi was born on April 1,1916 in Wischkwali  Poland (near Lodz) to Sarah and Yechiel Alter,  a  religious Zionist family. He studied in a Heder until the family made Aliyah when he was nine. They settled in Tel-Aviv. His father opened a grocery store at Hacarmel Street. Zvi studied in  various Yeshivas across the country. As a youth he joined ‘Brit-Hachashmona’im’, and like many in the movement, joined the National Military Organisation (Etzel). He underwent weapons training and was taken to combat Arab rioters in the 1936-39 riots, as well as the British regime. He installed a weapons hideaway at his parents’ store. Once, while removing weapons, a bullet was accidentally ejected; injured, his friends brought him to a doctor.

After the split in Etzel, 1940, he followed Yair to Lehi. On February 2, 1942 Yair was assassinated and activities ceased a while due to severe persecution and lack of organisation. A small group led by Tuviya Chenzion was organised and dug in deeply underground, believing that Yair was assassinated because of a traitor at the top. Therefore the movement cut itself from all contacts perceived as dubious, to continue its fight against the British. After Yitzchak Shamir escaped from Mizra Prison Camp and began re-organising the underground, all the group’s members joined the new organisation, including Zvi. Falling under British suspicion, he was arrested and imprisoned in Jaffa Prison where he was interrogated by the CID’s Officer Wilkin Lacking evidence, he was released. He then ceased activity to avoid re-capture.  For a while he worked in a packaging materials factory.

In 1942 he married Rachel nee Kalich; the couple had four children and many grandchildren and great-grandchildren. They began growing citrons in a Rishon Lezion orchard, and selling them in Tel-Aviv. After the ‘Black Sabbath’ he was arrested, sent to Latrun, but released three weeks later. Through  the years he recruited several members to Lehi. He lost his eldest son in the Yom Kippur War.

Zvi Yitzchak passed away on May 20,1977 and was laid to rest in the Kiryat-Shaul cemetery of Tel-Aviv.