"An event like this breaks through that denial and gets us to look at life-and-death questions," Cohen said.
Even if they're not profound statements, people are touched by final comments, more than they are moved by deliberately reflective, insightful statements made in times when nothing significantly changes afterward, she said.
Twitter and other social networks make it easier for those comments to spread quickly. For some, tweets by those killed — retweeted and appended by others, are the first time they put a name to who died.
"It's a pretty amazing concept that we can see what people are thinking just moments ago, and moments later their lives change," Cohen said.
It has happened before, most notably with the famous.
—Andrew Breitbart, the conservative blogger and publisher who died in March after collapsing while walking near his home, used his last tweet to apologize to a follower for calling him a "putz."
—Dr. Frank Ryan, a well-known plastic surgeon from Beverly Hills, veered off a cliff in 2010 just minutes after tweeting a picture of his dog looking out toward the ocean from a sand dune.
—Heavy D's final tweet late last year became as memorable as his rap hits when he wrote simply: "BE INSPIRED."
It goes beyond postings from the famous and highly publicized, though. Months of Facebook updates by a mother who died soon after giving birth to a son resulted in a memorable 2010 Washington Post story told through her posts. Her final post, less than 12 hours before she died, told of her fear at being transferred to another hospital for more evaluation and testing.
These glimpses, pecked away by fingers or thumbs in fleeting moments and amplified only when their significance becomes known, are spurring people to more publicly share spontaneous thoughts about moments of life and death. All it took here to open the floodgates were a couple 140-character messages, and the knowledge that the people who wrote them had died — mere moments or hours ago — in a very public tragedy.
Those brief glimpses still don't give us firm answers. But that's not quite the point.
"It really kind of intensified my whole emotional response to the whole tragedy," Kovach said. "It definitely just reminds us that even if our only common thread is that we both have a Twitter account, we're still humans and we're in this together."
Oskar Garcia can be reached on Twitter at http://twitter.com/oskargarcia .
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