Hester Rebecca Nepping was born in Amsterdam in 1774, the only child of master painter Johannes Nepping and Cornelia Schram. At 19, she married Jan Brummelkamp, a tobacco seller. Their business fell apart, prompting moves from Amsterdam to Loenen (now Hilversum) in 1800, then to Hall in 1805 where both worked at a paper mill. 

In 1808, Nepping inherited a house in Wijk bij Duurstede and 5,000 guilders in cash. They relocated there, and Jan opened a paper dyeing business—again, it failed. During this time, Hester began a clandestine affair with Gerrit Verkerk, the city messenger. The inheritance drained, they took in boarders: the elderly Beerenburg-Vinjole couple and their sister‑in‑law. The agreement: 3,000 guilders during their lifetime, plus more upon their death.

Things turned dark real quick. Mrs. Beerenburg, their first boarder, apparently had a sour personality—so Hester and her maid Adriana van Rijswijk allegedly conspired to murder her. On 31 August 1811, Mrs. Beerenburg fell ill and died—aring alarms only late. But that was just the beginning. On 9 November 1811, Hester’s elderly father, who was living with them, also died unexpectedly. Two days later, on 11 November, Jan Brummelkamp passed away too—each death sparking more suspicion.

Hester, van Rijswijk, and Verkerk (who supplied the arsenic) were arrested. All made partial confessions. The Assize court found two murders proven and sentenced them to death. Because the Netherlands had been annexed into the French Empire, they appealed to the Court of Cassation in Paris, which upheld the verdict.

On 15 June 1812, Hester, Adriana van Rijswijk, and Gerrit Verkerk were publicly guillotined in front of Nieuwmarkt in Amsterdam.