code: function killExtraIEProcess (pid, cb) {
      var scodef = 'SCODEF:' + pid
  
      // wmic.exe : http://msdn.microsoft.com/en-us/library/aa394531(v=vs.85).aspx
      var wmic = 'wmic.exe Path win32_Process ' +
        'where "Name=\'' + PROCESS_NAME + "' and " +
        "CommandLine Like '%" + scodef + '%\'" call Terminate'
  
      exec(wmic, function (err) {
        if (err) {
          log.error('Killing extra IE process failed. ' + err)
        } else {
          log.debug('Killed extra IE process ' + pid)
        }
        cb()
      })
    }
docs: Spawning iexplore.exe spawns two processes (IE does that). The way karma kills the browser process (hard kill) leaves the other process in memory.  The second process is created using command-line args like this: "C:\Program Files\Internet Explorer\iexplore.exe" SCODEF:2632 CREDAT:275457 /prefetch:2 Where the SCODEF value is the pid of the 'original' process created by this launcher.  This function kills any iexplore.exe process who's command line args match 'SCODEF:pid'. On IE11 this will kill the extra process. On older versions, no process will be found.