DP wrote:
Bay Lop was in civilian clothes and, under the Geneva Conventions, was subject to summary execution as a spy.

In the past, summary execution of pirates, spies, and francs-tireurs have been performed and considered legal under existing international law. Francs-tireurs (a term originating in the Franco-Prussian War) are enemy civilians or militia who continue to fight in territory occupied by a warring party and do not wear military uniforms, and may otherwise be known as guerrillas, partisans, insurgents, etc.

Though these soldiers could be legally jailed or executed by most armies a century ago, the experience of World War II influenced nations occupied by foreign forces to change the law to protect this group....The war also influenced them to make sure that commandos and other special forces who were caught deep behind enemy lines would be protected as POWs, rather than summarily executed as Hitler decreed through his 1942 Commando Order.

...Shortly after World War II, at the Nuremberg Trials, the Commando Order was found to be a direct breach of the laws of war, and German officers who carried out illegal executions under the Commando Order were found guilty of war crimes.