Obama has received a letter which was tested positive for 'suspicious substances'. A letter was sent to a Senator earlier today which tested positive for ricin, a chemical weapon used in attempted and plotted attacks in the US and UK. A third letter, sent to another senator, has also tested for 'suspicious substance'. The attacks are not thought to be explicitly related to Monday's bombing of the Boston Marathon, though has been theorised that it could be part of a [i]Turner Diaries[/i] themed series of 'inspirational' anonymous attacks on the state. Letters have been postmarked April 8th, so possibly unrelated in that case. Sender was a Mississippi man, name withheld.