Michelle Alyssa Go, Sandra Shells and Brianna Kupfer were murdered in random killings that have shocked America. Their deaths shine a spotlight on homelessness, violent crime and gender-based violence, writes Rachel Sharp

Vanessa Guillen, 20, was a young Fort Hood soldier when she confided to her mother that she was being sexually harassed. Within months, she was dead. Her older sister tells Sheila Flynn how the family’s American dream for Vanessa turned into a nightmare – and how they’re fighting for other military victims