At 1 p.m. on Dec. 31, 1910, West Virginia peach grower Charles Twigg called on his fiancee, Grace Elosser, at her home in Cumberland, Md. The two were to be married the following day. They closed themselves in the parlor and remained undisturbed until 2:30, when Grace’s mother looked in with a question. She found Charles sitting in a corner of the divan, with Grace leaning against him. Both were dead.

A post-mortem suggested traces of cyanide in their stomachs, but no container was found on the bodies or in the room. If it was not suicide, was it murder? The couple had led uneventful lives, and only Grace’s family had had access to the parlor. A jury returned a verdict of cyanide poisoning “at the hands of person or persons to us unknown.”

The matter remained at an impasse until Jan. 28, when, as an experiment, doctors J.R. Littlefield and A.H. Hawkins left two cats in baskets on the parlor divan, lighted the stove, and closed the door for an hour. Both cats died. The lovers’ bodies were exhumed, and an examination showed that they had died of carbon monoxide poisoning. The flue had been choked with soot, and the odorless gas had overwhelmed the couple.

The Elossers cleaned the flue and moved out the house, but nearly the same tragedy befell the two women who succeeded them. On Feb. 21, 1913, a neighbor happened to call and found both women unconscious in their chairs. It was discovered that two bricks had been placed in the flue to reduce its draft, and soot had again choked the narrowed opening.