Question: Whose assassination did the son of Yusupov Palace participate in?

Context paragraphs:
Franz Ferdinand (disambiguation): Archduke Franz Ferdinand was the heir to the Austro-Hungarian throne whose assassination precipitated World War I.

Archduke Franz Karl of Austria: Archduke Franz Karl Joseph of Austria (17 December 1802 – 8 March 1878) from the House of Habsburg was father of two emperors (Franz Joseph I of Austria and Maximilian I of Mexico) as well as the grandfather of Archduke Franz Ferdinand of Austria, whose assassination sparked the hostilities that led to the outbreak of World War I, and the great-grandfather of the last Habsburg emperor Karl I.

Yusupov Palace (Crimea): The Yusupov Palace (Ukrainian: Юсуповський палац ) is a palace located in the town of Koreiz, near Yalta in Crimea.  It was built for Prince Felix Yusupov-Soumorokov-Elston, father of Prince Felix Yusupov (1887–1967) in 1909 by Nikolay Krasnov, the architect responsible for the imperial Livadia Palace in nearby Yalta.  The palace, whose style may be described as Renaissance Revival and Roman Revival, boasts a romantic park with exotic plants and a wine cellar founded by Prince Lev Galitzine in the 19th century.

Livadia Palace: Livadia Palace (Russian: Ливадийский дворец , Ukrainian: Лівадійський палац ) was a summer retreat of the last Russian tsar, Nicholas II, and his family in Livadiya, Crimea.  The Yalta Conference was held there in 1945, when the palace housed the apartments of Franklin Delano Roosevelt and other members of the American delegation - the Russian delegation was housed in the Yusupov Palace, and the British in the Vorontsov Palace some five miles distant.  Today the palace houses a museum, but it is sometimes used for international summits.

Stephen Alley: Captain Stephen Alley was an engineer and MI6 (SIS) agent born in a House of Yusupov Palace, Moscow, Russia.  He was educated in both Russia and England and became experienced in building rail transport.  He is noted by many authors and documentaries for alleged involvement in the murder of Grigori Rasputin whilst working for the British Military Control Office in Saint Petersburg.  Alley was alleged to be the author of a notorious letter to John Scale on 25th December 1916 that, if authentic, is claimed by BBC History to be "the best proof of British involvement in Rasputin's murder"

Felix Yusupov: Prince Felix Felixovich Yusupov, Count Sumarokov-Elston (Russian: Князь Фе́ликс Фе́ликсович Юсу́пов, Граф Сумаро́ков-Эльстон ; 23 March [O.S. 11 March] 1887 – 27 September 1967) was a Russian aristocrat, prince and count from the Yusupov family, best known for participating in the assassination of Grigori Rasputin.

James King of William: James King of William (January 28, 1822 – May 20, 1856) was a crusading San Francisco, California, newspaper editor whose assassination by a criminal in 1856 resulted in the establishment of the second San Francisco Vigilance Committee and changed the politics of the city.  King was among the first newspapermen to be honored by the California Journalism Hall of Fame.

Rasputin the Mad Monk: Rasputin, the Mad Monk is a 1966 Hammer film directed by Don Sharp and starring Christopher Lee as Grigori Rasputin, the Russian peasant-mystic who gained great influence with the Tsars prior to the Russian Revolution.  It also features Barbara Shelley, Francis Matthews, Suzan Farmer, Richard Pasco, Dinsdale Landen and Renée Asherson.  The story is largely fictionalized, although some of the events leading up to Rasputin's assassination are very loosely based on Prince Yusupov's account of the story.  For legal reasons, the character of Yusupov was replaced by Ivan (Matthews).  Yusupov was still alive when the film was released, dying on 27 September 1967.

Moika Palace: The Moika Palace or Yusupov Palace (Russian: Дворец Юсуповых на Мойке , literally the Palace of the Yusupovs on the Moika) was once the primary residence in St. Petersburg, Russia of the House of Yusupov.  The building was the site of Grigori Rasputin's murder in the early morning of December 17, 1916.

Kokkoz Jami Mosque: The Kokkoz Jami Mosque, also known as Yusupov's Mosque, is located in the village of Sokolyne, Crimea.  In Crimean Tatar: Kokkoz means “Falcon”.  The mosque was built under the patronage of Prince Felix Yusupov in 1910 by a notable contemporary architect Nikolay Krasnov, the author of the imperial residence Livadia Palace.

Supporting paragraphs: Yusupov Palace (Crimea) Felix Yusupov
Answer: Grigori Rasputin