If you google on "Poisoners Handbook" you will find the information you are looking for I am sure.

Thank you much, hun. :) I've found a lot of information pertaining to the film "The Young Poisoner's Handbook", which is relevant and useful, along with a very interesting site with some ideas. That coupled with the research I conducted since my original request for help have helped immensely. (So, thank you again!

I'm playing around with one of some of the plants that contain lethal doses of cyanide (I'm amazed by how many plants contain cyanide, especially potatoes), which, with chronic ingestion, reacts just the way I need it to for the story. I just need to find something that isn't overtly bitter and thus easily detected.

I am also toying around with the possiblility of oleander. I just need to do more research on chronic poisoning versus instant lethal poisoning, and from that determine its practibility. Thus far I've only found one documented case of oleander being used to poison in small, reoccuring doses, and I need to actually order a copy of the report in order to obtain details on it. I just might do so, though.

So, if anyone has more ideas or suggestions, it would be greatly appreciated, once again. ^_^

I'm no scientist but I believe the oleander dosage needed for your delayed effect would too hard for an ordinary murderer to measure. I was always told that one drop could kill over a hundred people.

In my past life I raised llamas. There was a case of some llamas being killed by a poison in a wildflower - a type of Senecio found on the prairies. Evidentally the poison is slow acting and forms crystals in the liver. By the time the animals were dead the plants were long gone (I think it took six months). There was no treatment and no indication of a problem until it was too late. And the wildflower was common and looks like every other yellow blooming composite except that it is a spring bloomer and the poisoning appears to happen in the fall because of the delay.

I always thought tropical poison dart frogs would be an interesting weapon until I learned that outside of their native environment they lose their toxicity. It's all because of some poisonous ants they eat in the wild and not in captivity.

Cyanide tastes like a peach pit. Ask the guys in a plating shop. I worked in one for a short time once. It wasn't my 'cup of tea'.

One plant-based drink known for causing seizures and other neurologic problems with chronic intake is absinthe.

By the way, "oleander tea" has achieved some popularity among a credulous fringe as a purported anticancer agent.

Did you look up anything on Ricinis