in context to the above person, was he ever arrested?
Yes, by the British.
Joel Brand
While on the train, Brand was approached by two representatives of Zeev Jabotinsky's Hatzohar (Revisionist Zionist) party and the World Agudath Israel Orthodox religious party. They told him the British were going to arrest him in Aleppo: ""Die Engländer sind in dieser Frage nicht unsere Verbündeten""("the British are not our allies in this matter"). As soon as he arrived at the Aleppo train station on 7 June, he was stopped by a British man in plain clothes and pushed into a Jeep that was waiting with its engine running.

The British drove him to a villa, where for four days they tried to stop Moshe Sharett from meeting him. Sharett "fought a battle of telephones and cables," Bauer writes, and on 11 June he and the Jewish Agency intelligence group were finally introduced to Brand. The discussion lasted several hours. 
what is joel brand's profession? UNANSWERABLE who was he? He was a member of the Budapest Aid and Rescue Committee. what is this committee about? It was a small committee of Zionists in Budapest, who helped Hungarian Jews escape the Holocaust during the German occupation of Hungary. when was it established? UNANSWERABLE what do you mean by the term you referred to from which the hungarian jewish escaped? It was the World War II genocide of the European Jews. from where did this term originate? It comes from, "hólos", "whole" + "kaustós", "burnt offering". in which experiment was it involved? Medical experiments.
wiki:2381881
Joel Brand [SEP] Arrested by British
In Istanbul Brand was told that Moshe Sharett was unable to obtain a visa for Turkey. The Jewish Agency asked Brand to meet Sharett instead in Aleppo on the Syrian-Turkish border. He was reluctant; the area was under British control and he was afraid they would want to question him, but the Agency told him it would be safe and he left by train with two of its delegates. While on the train, Brand was approached by two representatives of Zeev Jabotinsky's Hatzohar (Revisionist Zionist) party and the World Agudath Israel Orthodox religious party. They told him the British were going to arrest him in Aleppo: ""Die Engländer sind in dieser Frage nicht unsere Verbündeten""("the British are not our allies in this matter").