A U.S. Capitol Police hazmat vehicle is parked at a mail processing plant in Prince George's County where a letter addressed to Sen. Roger Wicker, R-Miss., tested positive for ricin, Tuesday, April 16, 2013, in Hyattsville, Md. An envelope addressed Wicker tested positive Tuesday for ricin, a potentially fatal poison, congressional officials said, heightening concerns about terrorism a day after a bombing killed three and left more than 170 injured at the Boston Marathon. (AP Photo/Molly Riley)

Ricin letter saga: As it unfolded

Letters containing ricin found their way to a congressman and President Barack Obama. Here's a look at news alerts since the first instance.

FILE - This March 19, 2013 file photo shows Canadian singer Justin Bieber performing during a concert at Bercy arena in Paris. Bieber has visited the Anne Frank House in Amsterdam, with a museum spokeswoman saying the Canadian pop star wrote in the guestbook that he hoped Frank "would have been a Belieber" if she had lived. Museum spokeswoman Maatje Mostart confirmed Sunday, April 14, 2013 that Bieber visited Friday evening. (AP Photo/Francois Mori, file)

Germany: Bieber’s monkey going nowhere

German customs authorities said Tuesday that Justin Bieber's monkey is going nowhere for now even though the singer has apparently asked tha…