Social media aids angst over US shooting case

Thousands participate in a rally for Trayvon Martin, the teen shot by Neighborhood Watch patrol captain George Zimmerman, in Sanford, Fla., Thursday, March 22, 2012. Zimmerman's claim of shooting the teen in self defense has been questioned by community leaders. (AP Photo/Roberto Gonzalez)It started a couple of weeks ago with a few cryptic messages on Twitter and other social media websites: Where is the justice? and R.I.P. TrayvonMartin.