Question: Koestler was sentenced to death under the regime of which Spanish military dictator?

full_context: Document 1: Iñaki de Juana Chaos: José Ignacio de Juana Chaos (born 1955 in Gipuzkoa, Spain), better known as Iñaki de Juana Chaos, is a member of the Basque separatist group ETA. He was convicted of killing 25 people in 1987 and was originally sentenced to 3,000 years in prison. As a result of complicated sentencing guidelines, he became eligible for release in late 2004 after only serving 17 years. However, the Spanish Government prevented his release by accusing him of making terrorist threats in two articles written from prison. In August 2006, he started a hunger strike protesting his continued imprisonment but it ended after sixty-three days. Another hunger strike occurred from November 2006 until March 2007, it ended after he was moved from a hospital in Madrid to one in his home region of Gipuzkoa. After he left the hospital he was to be placed under house arrest, but on 6 June 2007, after the end of ETA's ceasefire he was sent to Aranjuez prison. On 2 August 2008, de Juana Chaos was released from prison.
Document 2: Spanish Testament: Spanish Testament is a 1937 book by Arthur Koestler, describing his experiences during the Spanish Civil War. Part II of the book was subsequently published on its own, with minor modifications, under the title "Dialogue with Death" (see below). Koestler made three trips to Spain during the civil war; the third time he was captured, sentenced to death and imprisoned by the Nationalist forces of General Franco. Koestler was at that time working on behalf of the Comintern and as an agent of the Loyalist Government's official news agency, using for cover accreditation to the British daily "News Chronicle".
Document 3: Augusto Pinochet: Augusto José Ramón Pinochet Ugarte (] or ] ; 25 November 1915 – 10 December 2006) was a Chilean general, politician and the dictator of Chile between 1973 and 1990; he remained the Commander-in-Chief of the Chilean Army until 1998. He was also president of the Government Junta of Chile between 1973 and 1981. His rule of Chile was a dictatorship.
Document 4: Francisco Franco: Francisco Franco Bahamonde (] ; 4 December 1892 – 20 November 1975) was a Spanish general who ruled over Spain as a military dictator from 1939 until his death in 1975.
Document 5: Fernando Barron: Fernando Barrón y Ortiz (1892–1952). Spanish military officer. One of the five commanders of the natives troops in Africa, he supported the military coup of July 1936 which started the Spanish Civil War. Later, he was one of the commanders of the Spanish Army of Africa in its advance towards Madrid. In November 1936 led the nationalist attack against the Madrid’s suburb of Carabanchel. In December 1936 he led one of General Varela’s mobile columns in the Second battle of the Corunna Road. In January 1937 he led a brigade in the Battle of Jarama. In May 1937, he took part in the nationalist counteroffensive during the Segovia Offensive. In June 1937, he led the 13th division in the Battle of Brunete in August in the Battle of Belchite and in March 1938 in the Battle of Caspe. During the Battle of the Ebro he led the Nationalist defense of the town of Gandesa. After the war, he was a minister of the Francoist dictatorship.
Document 6: History of Thailand (1932–1973): The history of Thailand from 1932 to 1973 was dominated by military dictatorships which were in power for much of the period. The main personalities of the period were the dictator Luang Phibunsongkhram (better known as Phibun), who allied the country with Japan during the Second World War, and the civilian politician Pridi Phanomyong, who founded Thammasat University and was briefly prime minister after the war.
Document 7: Spanish Republican government in exile: The Government of the Spanish Republic in exile (Spanish: "Gobierno de la República Española en el exilio" ) was a continuation in exile of the government of the Second Spanish Republic following the victory of Francisco Franco's forces in the Spanish Civil War. It continued to exist until the restoration of parliamentary democracy in 1977.
Document 8: Spanish 1977 Amnesty Law: The Spanish 1977 Amnesty Law is a law promulgated in 1977, two years after dictator Francisco Franco's death, that shields any Franco era crime from being put under trial. The law is still in force, and has been used as a reason for not investigating and prosecuting Francoist human rights violations.
Document 9: Francisco Rizzo: General Francisco Rizzo y Ramírez (November 28, 1831 - February 20, 1910) was the acting Spanish Governor-General of the Philippines, from August 13 to September 1898, after the Battle of Manila. He relieved General Fermin Jáudenes as Acting Governor-General on August 13. Sources reported that Rizzo relocated the Spanish capital from Manila to Malolos, which was also Aguinaldo’s capital. An uneasy truce occurred between the remaining Spanish and Aguinaldo. The French Consulate in Manila considered General Rizzo “to be a good man, but lacks leadership qualities”. During General Rizzo’s reign, General Elwell Otis relieved General Wesley Merritt on August 29, as Commander, Department of the Pacific, and as the U.S. Military Governor of the Philippine Islands. In General Otis’ reports, he never mentioned Governor-General Rizzo, but apparently communicated almost exclusively with Spanish General Diego de los Rios, who then commanded the remnants of the Spanish Army in the Visayas and south Philippines. Rizzo was ultimately replaced by de los Rios as Governor-General in September 1898.
Document 10: Imprisoned Graves: The "Imprisoned Graves" are a set of graves in a small cemetery located in the Central Jail of Nicosia, where 13 EOKA fighters, during the 1955-1959 liberation struggle for the liberation of Cyprus from the United Kingdom, were interred. Nine of them were hanged by British executioner Harry Allen, three were killed in action and one died in hospital from wounds.
Document 11: Koestler Trust: Koestler had been detained in three jails in separate countries. In Spain, he was sentenced to death in 1936 for espionage under Francisco Franco's regime. Here, he witnessed many executions, and was held in solitary confinement. He was arrested in France a few years later and held in the Le Vernet Internment Camp for subversion. Koestler was released and fled to England, where he was held at Pentonville as a suspected illegal immigrant.
Document 12: Murder of Lesley Molseed: The murder of Lesley Molseed, an 11-year-old British girl, occurred on 5 October 1975 in West Yorkshire, England. Stefan Kiszko, a intellectually disabled man who lived near Molseed in Greater Manchester, was wrongly convicted of sexual assaulting and murdering her, and served 16 years in prison before the conviction was overturned. Kiszko's mental and physical condition deteriorated while he was in prison, and he died 18 months after his release in 1992, before he could collect money owed to him for his suffering. His ordeal was described by one British MP as "the worst miscarriage of justice of all time." Evidence that Kiszko could not have done the crime was suppressed by three members of the investigation team, who were initially arrested in 1993 before charges were dropped.
Document 13: Punk rock in Spain: In Spain, the punk rock scene emerged in 1978, when the country had just emerged from forty years of fascist dictatorship under General Franco, a state that “melded state repression with fundamentalist Catholic moralism”. Even after Franco died in 1975, the country went through a “volatile political period”, in which the country had to try to relearn democratic values and install a constitution. When punk emerged, it “did not appropriate socialism as its goal”; instead, it embraced “nihilism”, and focused on keeping the memories of past abuses alive, and accusing all of Spanish society of collaborating with the fascist regime.
Document 14: Arthur Koestler: Arthur Koestler, ( ; ] ; Hungarian: "Kösztler Artúr" ; 5 September 1905 – 1 March 1983) was a Hungarian-British author and journalist. Koestler was born in Budapest and, apart from his early school years, was educated in Austria. In 1931 Koestler joined the Communist Party of Germany until, disillusioned by Stalinism, he resigned in 1938. In 1940 he published his novel "Darkness at Noon", an anti-totalitarian work that gained him international fame. Over the next 43 years, from his residence in Britain, Koestler espoused many political causes, and wrote novels, memoirs, biographies and numerous essays. In 1968 he was awarded the Sonning Prize "for [his] outstanding contribution to European culture" and in 1972 he was made a Commander of the Order of the British Empire (CBE). In 1976 he was diagnosed with Parkinson's disease and in 1979 with terminal leukaemia. In 1983 he and his wife committed suicide at their home in London.
Document 15: Segovia prison break: The Segovia prison break (Spanish: "Fuga de Segovia" ) occurred in Segovia, Spain on 5 April 1976 when 29 political prisoners escaped from Segovia prison. This was the largest prison break in Spain since the Spanish Civil War. The prisoners escaped by means of tunnels they had excavated and then through the prison's drainage system. Hidden in a truck, they fled in the direction of the French border. Before reaching the border, their escape plans broke down and they found themselves stranded and lost in woodland in Navarre. Most of them were recaptured after a confrontation with the Civil Guards in Espinal, during which one of the prisoners was shot dead. The remaining four escapees managed to cross the French border and were detained by the French government, but escaped once again. In 1977, the Spanish authorities declared a general amnesty, after which the escapees were freed or could return to Spain.
ground_truth: Francisco Franco Bahamonde