She was a good enough judge of character to see that Elettra had the revengeful disposition common to many of the southern hill people, and the woman's dark complexion, sombre eyes, and thin frame would all help to strengthen the impression in the mind of an unprejudiced judge.
She intended to make it appear that Elettra had poisoned the whole family, beginning with Matilde herself, out of revenge for her dead husband.

Veronica was to die, but Gregorio and Matilde herself would only suffer a certain amount of pain for a few hours, and then recover.
She had begun by half poisoning herself, both to remove all suspicion, and as a sort of experiment, to be sure that she was giving herself and her husband a sufficient amount to produce the real symptoms of poisoning by arsenic.

No half measures, no mere acting, would be of any avail.
The stuff in the package wrapped in coarse paper was an almost pure salt of arsenic, sold by grocers as rat-poison.
The two small lumps of sugar and arsenic medicine were for herself and her husband; the large lump of almost pure poison was for Veronica.
In the examination which would follow upon the deed, the package of rat-poison would be found under the chest of drawers in the maid's room, half empty.

It would be discovered that every alternate paper of Matilde's medicine had been tampered with, and it would be supposed that Matilde had at the first time taken one of those containing poison, whereas the doctor who had attended her had taken the next, which was untouched and only had medicine in it.
She intended to make tea on the following afternoon in Veronica's room.
She could easily find an excuse for bringing in Gregorio who, like many modern Italians, had acquired the habit of drinking tea every day.

She herself would make the tea, and put in the sugar and cream.