Kai Christian Middelthon Holst (24 February 1913 – 27 June 1945) was a Norwegian seaman, fur farmer and resistance fighter during World War II.

[2] Holst's demise was so much talked of at the time that the Milorg leadership issued a statement in the Norwegian newspaper Aftenposten in July 1945.

After Norway was invaded and occupied by Nazi Germany Holst soon, despite his bad health, started working with the main Norwegian resistance organisation, Milorg.

He was recruited in 1941 by his brother-in-law, the officer Lars Heyerdahl-Larsen[18] and was soon given important tasks[12] and gained a reputation as the most action-oriented man in the secretariat of the central leadership (Sentralledelsen).

[11] In his report about his work during the war Jens Christian Hauge was highly approving of "Kaka", as Holst was called informally, and especially recognised him among his colleagues.

[25] When Jomar Brun (known for his involvement in Norwegian heavy water production) and his wife had to flee to Sweden, it was Holst who through Milorg's chief of communications, Salve Staubo, organised an undercover apartment in Oslo for the couple.

[18] Holst participated in the meeting at the turn of the year 1942 when Milorg was reorganised with Jens Christian Hauge as Inspector General (known as "big I").

[28] Holst had an important role during the Osvald Group's fire-bombing of the work-service office in Pilestredet in Oslo on 20 March 1943,[29][30][31] which Milorg hesitantly agreed to,[30][32] whose aim was to destroy archives of people assigned to work service for the Nazi regime.

[34][35][36][37] Holst was a skilled undercover operator, fully aware of the risks of being captured, and always carried a gun and a poison pill with him so that if he was caught, he could commit suicide and not reveal information about the organisation.

[42] Around the same time Holst was mentioned by Säpo in connection with an espionage affair in which the Norwegian intelligence agent Finn Jacobsen was involved.

[10] After the German capitulation in May 1945, Holst was working on closing the various storage bases that Norwegian resistance fighters had established on Swedish soil, and travelling back and forth between Sweden and Norway.

[22] The same day he unexpectedly travelled back to Stockholm[46] and on the morning of 27 June was found dead at the top of the staircase in an apartment building at Rindögatan 42 on Gärdet.

[2] He was found by the porter's wife, shot in the right side of the head, lying in a pool of blood at the top of the staircase, outside the door to the elevator room.

[4][6][7][9] Among the theories colleagues and friends put forward about a possible murder was liquidation by a foreign intelligence service, be it from Germany, Sweden, the Soviet Union or the US.

[58] Ole Otto Paus, then an army captain, later a major general, was married to the sister of Holst's widow and in 1945 in Oslo he saw the documents from the police investigation when he tried to check the case.

The museum used material collected by retired Supreme Court judge Einar Løchen[50] on behalf of Ole Borge, one of Milorg's leaders and veterans, who believed Holst had been liquidated.

[65] Borge and Løchen believed it was the communists who had murdered Holst,[66] and the same view was held by the former XU agent Wiggo Ljøner.

[68] Professor Tore Pryser claims that with the level of detail Säpo went into in similar cases there must have been a dossier: "Everything points to the information about Holst having been destroyed.

He first stated that the liquidation had been ordered at "high levels within Milorg" but later on changed his opinion, in consultation with the retired landshövding and historian Per Nyström, to its having been done by the Swedes in cooperation with the Norwegians.

[81] Holst's close colleague during the war, the Milorg leader Jens Christian Hauge, has been criticised for refusing to assist in casting light on the case.

"[85] The question has been asked whether Kai Holst's death could be connected with his task at Lillehammer, a hypothesis primarily put forward by the historian Tore Pryser.

[49][86] Odd Feydt stated that when Holst travelled back to Stockholm, he was tailed from the moment he passed the Norwegian-Swedish border.

[87] Kai Holst never received any decoration from Norwegian authorities for his wartime efforts, in spite of his superior Wladimir Mørch Hansson recommending one to the council of the resistance forces in January 1946.