1889 4 May	Born in Utrecht, the son of Pieter Grootendorst and Teuntje van Egdom. His parents were members of the Nederduits Reformed Church.
1912 16 Nov	Joins the police force.
1915 28 July	Marries Louisa F. van Heerde.
1916 6 Feb	He now works at the Kattenburgergracht police bureau. Daughter Louisa is born.
1919 13 Feb	Daughter Wilhelmina Antonia is born.
1936 27 Aug	Divorces from Louisa van Heerde.
1939 21 June	Marries Dieuwertje Dil, who has two sons from an earlier marriage (Klaas and Dirk).
1941 5 July	Joins the NSB (the Dutch Nazi Party, member #155414).
1942 spring	Is transferred to the police headquarters.
1943	Starts work as an inspector at the bureau Joodsche Zaken where he works under the supervision of Kempin, of the Sicherheitspolizei (German security police).
1944 March	Is no longer working at the bureau Joodsche Zaken.
4 Aug	Is on the team arresting Anne Frank and the other people in hiding in the back house at Prinsengracht 263.
Sept	Transferred to Zunderen and Apeldoorn, doing espionage work monitoring political activists.
1945 20 March	On his request, he is transferred to Amsterdam again, working in the Bureau Kattenburg.
8 May	Is arrested regarding his wartime activities.
1947 17 March	The special court sentences him to life imprisonment. (He then is in the Leeuwarden jail.)
1952 5 June	The Queen changes his life sentence to just 18 years!
1955 6 May	For the celebration of the 10th liberation anniversary, Grootendorst is given a 270 day reduction to his sentence.
1961 24 Dec	Divorces from Dieuwertje Dil.
1964 7 Jan	Is called as a witness on the trial against Silberbauer. (In the file is a note that he is working an office worker in Amsterdam, and is living at Corantijnstraat 22-II.)
1973 2 July	Dies in an elderly home in Utrecht at the age of 84.