Rachel Jeantel said she told Trayvon to run after he said: 'The n**** is still behind me'
She said she heard Trayvon ask the man 'Why are you following me?' and that he said, 'What are you doing around here?'
Defense expected to call her credibility into account
Admitted she lied about being sick on day of funeral
'I felt guilty...I was the last person that talked to their son', she said
Earlier a neighbor said she heard a boy's voice cry for help before a gun shot rang out