Preliminary tests indicate ricin was found in letters sent last weekend to New York City Mayor Bloomberg and the director of Mayors Against Illegal Guns. The American Postal Workers Union said the letters were postmarked in Shreveport, Louisiana.
"The letter obviously, referred to our anti-gun efforts but there's 12,000 people (who) are going to get killed this year with guns and 19,000 that are going to commit suicide with guns, and we're not going to walk away from those efforts," Bloomberg said.
There is no known cure for the toxic substance. A small amount can kill a person within 36 to 48 hours.
CNN's Deb Feyerick reports on Tamerlan Tsarnaev's official cause of death. His death certificate lists “gunshot wounds of torso and extremities” and “blunt trauma to head and torso.” Graham, Putnam, and Mahoney Funeral Parlor in Worcester does not yet have a burial site for the man accused of bombing the Boston Marathon with his younger brother on April 15.
CNN's Deborah Feyerick reports on what a gruesome 2011 murder has to do with one of the Boston bombing suspects.
The slaying of one of Tamerlan Tsarnaev's best friends in September 2011 is now being reviewed by a "wider group of eyes,"a source close to the Boston bombing investigation tells CNN.
The killings of Brendan Mess and two others - all of whom had their throats slit - in Waltham, Massachusetts, remain unsolved. The Middlesex County district attorney's office said at the time that the three victims were killed by "sharp force injuries of the neck."
District Attorney Gerry Leone said days after the crime that the victims and two unknown perpetrators appeared to know each other and that it was not a random crime. No suspects were named or arrests made in the case.
As investigators scramble to figure out who killed two Texas prosecutors, suspicions abound over whether the Aryan Brotherhood of Texas played a role.
Authorities have not officially linked the two slayings, nor do they know whether the white supremacist group ordered the attacks.
But a series of events leading up to the killings have raised questions about the group's possible involvement.
As Andrew Mason, co-founder of Groupon, leaves the company with a memorable letter, Deb Feyerick looks at other unforgettable resignations.
The Long Island Power Authority is facing accusations of negligence over its response to the Superstorm Sandy outages in New York. CNN's Deb Feyerick reports.
CNN's Deb Feyerick visited St. Johns Episcopal Hospital in Queens, New York, which took in displaced Sandy victims but is unable to recoup the costs - nearly $3 million.
"EMS was lined up with stretchers out the ambulance door. They couldn't even get into the Emergency Room. It was horrible," says Sharon Behar, the vice president of the hospital.
At 14 feet above sea level, elderly and disabled residents in the Rockaways knew they would be safe in the hospital after they were forced to evacuate. The needs varied with some patients requiring electricity for their medical devices, a stable location, or prescription refills.
CNN's Deb Feyerick reports on the Rockaways, a neighborhood in Queens, New York without electricity 12 days after Sandy. New York Governor Cuomo says the Long Island Power Authority "should be held accountable for their failure" to restore power to 150,000 homes. Burglary there has increased by 7%, police say. One resident worried about defending the belongings he has left tells CNN "They just forgot about us."