* Country heads into fourth week of unrest over police brutality * Biden VP contenders in spotlight after Rayshard Brooks killing * Protests in Atlanta over shooting of Rayshard Brooks – liveLeading Democrats said on Sunday the killing of Rayshard Brooks in Atlanta underlined the need for significant change in US law enforcement, as the country headed into a fourth week of unrest over police brutality and systemic racism.Brooks, 27, was shot on Friday night after officers responded to a call about him falling asleep in his car while in the drive-thru line at a Wendy’s fast-food restaurant. Video showed Brooks and officers in lengthy conversation before an altercation erupted.