Herman Koch is a non-canonical character who was created for ITV's 2007 adaptation of the novel At Bertram's Hotel. Koch was a guest of the hotel at the time Miss Marple was staying there.
During the stay, Koch impersonated Canon Pennyfather. However Miss Marple got suspicious when she realised that Koch did not know the bible well: he only ever quoted from the book of Psalms. He was also unfamiliar with the structure of the Church of England. He claimed to be the Canon of Ely (in the original novel, Miss Marple had an uncle Thomas who was the Canon of Ely). However Koch thought the diocese of Ely was part of the province of York when it should have been part of the province of Canterbury.
Towards the end of the show, Mr Mutti and Ladislaus Malinowski, both Nazi hunters in this adaptation, confronted Koch. At first he protested his innocence but then broke down and started cursing in German. Malinowski revealed that Koch was in fact an ex-Nazi known as "The Butcher of Riga". He was a fugitive using an established escape route (a "ratline"). centred on the hotel. Koch was what the hotel codenamed a "Blake guest". This was a special category of guests, Nazi fugitives, who arrived by "Blake Air", an airline ran by the hotel owner Sir Richard Blake. After sheltering in the hotel for a while, they are then provided safe passage to South America. For this service, the "Blake guests" were expected to pay with looted artwork which the hotel then sold to interested buyers. One of the artworks was a Rembrandt which Koch had looted from Mutti's family home after murdering his family. It was seeing this painting in the hotel that put Mutti on his trail. Malinowski wanted to shoot Koch but Bess Sedgwick persuaded him to let Inspector Larry Bird take him into custody.
Herman Koch was portrayed by Charles Kay.