A letter that reportedly claimed to be contaminated with ricin was sent Monday to the home of Republican Sen. Susan Collins in Bangor, Maine. A hazmat team investigated her house and preliminary tests indicated there was no threat to the public. Sen. Collins has been the target of attacks before and since she cast a decisive vote this month to confirm Brett Kavanaugh to the Supreme Court.Subscribe to the "CBS This Morning" Channel HERE: http://bit.ly/1Q0v2hEWatch "CBS This Morning" HERE: http://bit.ly/1T88yARWatch the latest installment of "Note to Self," only on "CBS This Morning," HERE: http://cbsn.ws/1Sh8XlBFollow "CBS This Morning" on Instagram HERE: http://bit.ly/1Q7NGnYLike "CBS This Morning" on Facebook HERE: http://on.fb.me/1LhtdvIFollow "CBS This Morning" on Twitter HERE: http://bit.ly/1Xj5W3pFollow "CBS This Morning" on Google+ HERE: http://bit.ly/1SIM4I8Get the latest news and best in original reporting from CBS News delivered to your inbox. Subscribe to newsletters HERE: http://cbsn.ws/1RqHw7TGet your news on the go! Download CBS News mobile apps HERE: http://cbsn.ws/1Xb1WC8Get new episodes of shows you love across devices the next day, stream local news live, and watch full seasons of CBS fan favorites anytime, anywhere with CBS All Access. Try it free! http://bit.ly/1OQA29BDelivered by Norah ODonnell and Gayle King, "CBS This Morning" offers a thoughtful, substantive and insightful source of news and information to a daily audience of 3 million viewers. The Emmy Award-winning broadcast presents a mix of daily news, coverage of developing stories of national and global significance, and interviews with leading figures in politics, business and entertainment. Check local listings for "CBS This Morning" broadcast times.