Asher was born in 1925, in the Polish town of Rozyszcze, to Yisrael and Yona Becker. He studied in the Tarbut Hebrew school and joined Beitar at a young age. When the Germans invaded Poland, the family was sent to the Warsaw Ghetto. Asher sought some way to escape and join the partisans, which they finally managed to do by fleeing the ghetto and hiding in a pigsty owned by their non-Jewish Polish friends. Asher risked his life to go out at night and find bread for his family among the hostile surrounding villages. Asher hid for eight months in this manner, then joined the partisans and participated in their campaigns of sabotage and guerilla warfare against the German occupiers. On one occasion he was apprehended by the vehemently antisemitic Ukrainians, who condemned him to die, but he managed to escape and rejoin the partisans. When World War II ended, he wanted to make aliyah, but this proved quite difficult. He spent a long time in Italy trying to get to the Land of Israel.
Finally, he made his way on to the Mapilim ship Palmach, reaching the shores of the Land of Israel on 15 May 1946. However, the British spotted the ship and opened fire. Asher leapt into the water and swam to shore. The British caught him and exiled him to Cyprus, along with thousands of other Mapilim who had not managed to slip through. He stayed in that camp until early 1947, when he finally reached his destination. To honor his father, he changed his last name to Yisraeli, like his older brother. He now had the duty of caring for his mother and grandmother, who had made it to Kfar Saba in the meantime.
He took whatever job he could: first as a photographer and then working in a citrus juice factory in Kfar Saba, much like his older brother Yehoshua, a Lehi member who had broken out of Acre Prison.
Asher too joined Lehi, but before he could finish his operational training, the War of Independence began; so, he joined the IDF with all the Lehi members, serving in Battalion 82 of the 8th Brigade. He fought in the battles for Yehudia, Lod, Ramleh and the Negev.
Asher fell on duty, as a machine-gunner, in the battle for Iraq al-Menashiya (Operation Yoav) on 16.10.1948. At first, he was buried in Gat, but on 6 Tishrei 5710, 29.9.1949, he was re-interred at Nahalat Yitzhak Cemetery.