The end of Haigh's spree of petty crime and murder came when he identified his next target as a wealthy widow - a fellow resident at the Onslow Court Hotel where he was staying.
As an unmarried, elderly widow with evident personal wealth, she must have seemed to have been the ideal target for Haigh - and it didn't take him long to strike up a relationship with Mrs Durand-Deacon. In conversation she mentioned that she'd had an idea for creating artificial fingernails. To Haigh - now posing as an engineer - this was the perfect pretext under which to lure her to his Crawley "workshop."
Once through the door, he shot her coldly in the back and hauled her body into the acid. Denuding her of her possessions, he took ownership of a lambswool coat and various items of jewellery.
But this time, Haigh had overreached himself. Hardly friendless, Mrs Durand-Deacon was reported missing within 2 days and with Haigh's record of fraud and theft it wasn't long until the police were knocking at his door.
For Haigh it was the end of the line. When police searched, they found a dry-cleaning ticket for Mrs Durand-Deacon's lambswool coat. More came to light in the form of records pertaining to his earlier victims - the McSwanns and the Hendersons.
Finally, detectives began to examine the 'sludge' found in barrels at the back of the warehouse. The forensic experts soon found 3 human gallstones and the remains of a set of dentures. In court, these would conclusively prove to have come from Mrs Durand-Deacon and put the noose around Haigh's neck.