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
The Duke and Duchess of Cambridge were left cautiously watching every step after making an impromptu visit aboard a steam train.
Scientists concluded 12.5% of cardiovascular deaths could be avoided if more Britons changed their diets.
Chelsea Clinton has brushed off Donald Trump's threat to bring up her father's infidelities in a recent interview.