Fox News reporter Chad Pergram has tweeted that the letter sent to Barack Obama and the letter sent to Senator Roger Wicker yesterday - which tested positive for the poison ricin - contained 'similar language' and were 'signed identically'.
Letters sent to Obama & Wicker contain similar language and are signed identically.
More top news
A dog has been found with its paws frozen to the ground in a New York park after being chained to a tree.
Dramatic footage has emerged of a mother and her toddler being rescued after their car plunged into an Amsterdam canal on Tuesday.
Beth Tweddle has begun walking unaided following neck surgery after injuring herself during training for TV reality show 'The Jump'.