Through this work carried out between the years 1942 and 1945, Castellanos succeeded in saving about 40,000 Jews. The Yad Vashem institution noted that after the 1944 elections, the new president of el Salvador, Salvador Castaneda Castro, unlike his predecessor, had his country get involved in the protection of the Jews in places like Hungary and provided support for Castellanos in his rescue mission.
Currently thousands of these certificates which granted Salvadoran nationality to Jews in Europe are exhibited in the Holocaust Museum in Washington, D.C.
Castellanos married Maria Schürmann of Switzerland, and the couple had three children. When the Second World War was over in 1945 he was sent to London and retired in 1972 at the age of 79.
He returned to El Salvador where he led a quiet life until he died in 1977, without having been awarded any recognition for his work.
After his death, several institutions began to hold tributes in memory of Colonel Castellanos.
In 2010 when it was announced that he would be awarded the title of "Righteous Among the Nations," the El Salvador Minister of Foreign Relations, Hugo Martinez, said that the Salvadoran diplomat "stood out for his humanism and for his work in aiding a people which in their time was persecuted and whose existence was threatened."
The ambassador of Israel in the Central American country, Mattanya Cohen, said that Castellanos is the fourth Latin American to receive this tribute.
In late June 2017, the embassies of Israel and El Salvador to the Holy See held an event in Rome to honor the memory and the work of José Arturo Castellanos. A video was also shown there of the testimony of a Jewish man who obtained Salvadoran citizenship and was able to escape with his family.
In a press release announcing this event posted on the website of Diplomatic Missions of Israel in the World, noted that Catellanos "in a time when many remained indifferent to human suffering, he was one of the few heroes who opposed an absolute evil in order to save the lives of thousands of Jews."