Who silenced Pakistani social activist Sabeen Mahmud?

Aired: 4/27/2015 | 0:04:52 | Clip
Human rights activist Sabeen Mahmud was murdered outside her cafe in Karachi, Pakistan, on Friday. Her death came shortly after she hosted a talk on the killing and disappearances of political activists in Pakistan. Special correspondent Fred de Sam Lazaro, who interviewed Mahmud last month, joins Gwen Ifill to discuss Mahmud’s life and death.