Malachi was born on December 12, 1912 in Zikhron-Ya’acov, to his mother Sarah and  father Zvi, whose brother Fischel was the father of Aharon, Sarah, Alexander and Rivka Aharonson. At a young age his parents sent him to study at the American College Beirut-Lebanon, as  customary then. In 1936 Malachi married Sarah Fruman, native of Safed; they had a son and a daughter.

They would eventually be blessed with seven grandchildren.

In 1941, height of World WarII, Malachi enlisted in the British army  and served for the entire duration of the war, first in Egypt – in the mapping department – later in Italy. At war’s end, after his release, he returned to Zikhron-Ya’acov and joined Lehi. He dedicated most of his time to gathering intelligence, recruiting new members and supporters, finding hideout places for wanted members  seeking refuge from the British Police

(and imprisonment) and  securing storage places for weapons. He acquired weapons and ammo from British policemen  he’d established relations with, at the small roadside restaurant in the entrance to Zikhron. On September 17, 1948, Lehi members in Jerusalem (still unincluded within Israel’s borders) assassinated UN mediator Count Bernadotte, who was hostile to the State of Israel and who promoted chiefly Arab interests. As a result, Israeli authorities arrested all Lehi members not serving in the army at the time. Malachi was arrested  and imprisoned at Jaffa Prison, where they gathered about two hundred Lehi members. Following several prisoners’ escape, he was transferred with his friends to Akko, then to Jalameh Prison. He took part in the long hunger-strike there, which ended with everyone’s  release. He then worked as a truck driver to earn a living. Eventually he joined the Mapai Party and was appointed secretary of Zikhron-Ya’acov’s Workers’ Council. In 1960 he left Zikhron to join son Zvi at Moshav Bitsaron (near the Hazor airport). He was appointed secretary of the Workers’ Council of Gan-Yavneh. Malachi was greatly active in absorbtion of immigrants and helped in their transit living quarters, the ‘Ma’abarot’. He passed away May 1981 and was laid to rest in the Cemetery of Moshav Bitsaron.