So speacking about perfet murders..and getting away from the gov. mail box

Oxalic acid poisoning

    

Oxalic acid is a poisonous, colorless substance. This article discusses poisoning from swallowing oxalic acid.

https://medlineplus.gov/ency/article/002479.htm

which is very sweet flavour it goes well in any cake ....

http://www.ebay.co.uk/itm/12-5kg-oxalic-acid-Hull-Deck-GRP-cleaner-stain-rust-remover-/192061350958