Summary. It was the Colonel, and not for gain but for affront; Effie had priced his remaining breath aloud in his hearing, and he answered it with the hall sabre in the gallery that same evening. Here is how I came to it.

The Reckoning. The death falls between 8:45 and 9:15, by Dr Quill's own reckoning, the gallery being cold and the body still warm when found. Colonel Cecil Cruikshank was chalked by the tailor at 8:30 and went out to the hall mirror, and says he then sat in the gun-room. Mrs Gow found that room empty at 8:40, and he was not there when the port was carried in. He was next seen at 9:12, coming up the corridor from the gallery end, his coat afterwards found in the gun-room with the chalk smudged down the right side and the right cuff damp — a man who had been somewhere wetter and rougher than a fireside chair. The sabre had lived eleven years in the elephant's-foot stand, a house object any resident might lift without thought, and it was found across the pins-tray by the body, put back in the stand by morning. No weapon brought, no staging arranged, no signature but a temper that has put a chair through a window before now and a barometer through a wall — Mrs Gow keeps the drawer of hinges against it.

The other names in the house fall away on plain fact rather than character. Nan Pringle, who stood to gain by Effie's removal if anyone did, was in the tailor's chair under Mr Pettigrew's chalk without a break from 8:45 to the cry at 9:15, the tailor and Fifi both swearing to it — she could not have been at the gallery's near end with a sabre while sitting fixed at its far end for a stranger's needle. Aziz had motive of a kind in the jewel Effie priced, but the jewel sat untouched at his throat that evening as it does every evening, and he stood at the hall mirror the whole window through, watched continuously by Zane at the door. Lady Lavinia was below stairs with Mrs Gow from 8:35 to the cry, and Effie had paid her guinea again that very morning — an arrangement running smoothly is no cause for murder. Dr Quill's gig was still on the Kirk road at 8:45; he did not reach the house until 9:05 and had no time in the gallery before the body was found ten minutes later.

The motive, when it is laid out plain, is a small and ugly one. Effie Strange was the Colonel's heir-presumptive, and had been spending against the inheritance for months — a pawn-ticket, a chemist's bill, debts at three houses in the town, two refused advances. In her coat pocket, surrendered whole to the tailor as his custom required, was a ledger kept in her own hand across four months, tracking the Colonel's short breath, his physician's visits, the days his heart would bear the port and the days it would not. The last page was a sum, headed with a date and a question-mark, as though she were totting up how much longer she need wait. His letter to Mr Dunsire, asking him to attend upon the will, sat franked on the salver — the money already tilting, and Effie no doubt aware of it. At half past eight, waiting her turn behind the screen, she asked Quill — not quietly, with Nan and Fifi both in earshot, and the tailor besides — how long the Colonel's breath would hold, and whether a dying man ought to be signing papers. He came round the screen a moment after and heard the end of it, or near enough. A man may forgive being refused his temper over a barometer. He does not easily forgive being counted into his grave, aloud, by the girl who spends his money before he is in it. He took the sabre on his way down the corridor and answered the sum in the only currency he had left to spend. I have set the charge against Colonel Cecil Cruikshank, and the file, such as it is, may close — the third this twelvemonth, by my count, and the year not yet out.

The Colonel took the sabre and retired for tea,
While Effie found the gallery less cheerful than the sea;
The screen fell down, the chalk went white,
And household duties carried on quite right.
The moral, be watchful where household favours turn,
We vow to remember—then forget what we learn.