Tracey had been planning this for a very long time. As soon as her hurt had been replaced with anger, she had started plotting revenge. Unfortuneately, the thug hadn't inadvertantly killed the boy. It seemed she had to take things into her own hands. Why she thought someone else would finally come through for her was a mystery. One really did have to do things themselves to have them done right, trite as the phrase was.
Poison had come into her head ages ago, but how to do it was the challenge. She had chosen cyanide, hoping St. Mungo's wouldn't have a spell to counteract it. Muggle poison could be suspicious, but Neville knew more than one muggleborn. It wouldn't be traced back to her. Gift food was the best way to do it. That would eliminate the need to sneak into the house entirely. Cookies: Oatmeal with currant and milk chocolate, Fudge with white chocolate chip, Snickerdoodles, and Plain sugar cookies with ornate icing. She had the housekeeper make them, and slyly slipped the cyanide into each batch as she wasn't looking.
The tin she got from a bakery in Hogsmeade so it would look official, but the card was the real challenge. Nobody in their right minds would eat annonymous cookies even if the tin was still magically sealed. It took some looking into family trees to find the name of a relative. In the end, she signed the card with the name of an elderly aunt with carefully altered handwriting and sent the package away with an anonymous post owl.
With any luck, the Prophet would be reporting the unfortunate death of Neville Longbottom by morning. Tracey was pleased. For the first time since her brother was sent to boarding school, she possessed an inner peace.