Even during the riots that opened in 1936, Dr. David Mosinzon continued to make his rounds in the Arab villages providing help to the Arabs which he knew in culture and language.
On top of his work he was active in security and settlements of the area. In this capacity he went out on September 14, 1938, with two other Haganah members, Haim Shturman and Aharon Atkin, to find locations for two new settelments, Kefar Rupin and Neve Eitan in the Beit Shean valley.
On their way from Tel Amal to Tirat Tzvi, their vehicle went on a mine and the three were killed.
Gan Hashlosha (aka Sachne) was also named after the three.