Boost was born in 1928 in Germany and grew up in the immediate post-war period; he was stealing from the age of six and was in institutions as a child. He worked as a labourer near Dusseldorf and had a wife and children.
Between 1953 and 1956 he attacked couples in parked cars in the woods and lanes around Dusseldorf, with an accomplice named Franz Lorbach. Bernd Serve, a lawyer, was shot in January 1953. Friedhelm Behre, twenty-six, and his girlfriend Thea Kurmann were shot and their car pushed into a canal in November 1955. A woman named Wissing, twenty, and her companion were attacked in February 1956. The pattern involved gas or chloroform in some accounts and shooting in others, and Lorbach later described experiments with cyanide. Those named in the record are Bernd Serve; Friedheim Behre, twenty-six, and his girlfriend Thea Kumann; and a young woman recorded only as Fraulein Wissing, twenty, with her companion Peter Falkenberg. German reporting called him the Doubles Killer, because he attacked couples.
He was arrested on June 6, 1956, caught in the woods with a loaded weapon. Lorbach confessed and gave evidence against him.
He was convicted in 1959 of the murder of Serve and sentenced to life imprisonment. The other killings were charged and not proved to the court's satisfaction, and he denied everything throughout. Lorbach received six years.
The count of five in this roster is the series attributed; one murder was proved. The case ran in the German press as the Doppelmorder von Dusseldorf and the accessible record is largely that reporting and the summaries taken from it.