Maria Stubbings, of Chelmsford in Essex, was strangled with a dog lead in 2008 by Marc Chivers, who had already killed a previous girlfriend.
Her brother Manuel Fernandez has told ITV Daybreak that the family have been calling for a public inquiry.
He said: "This highlights issues around domestic violence with one police force but it's actually a national problem."
More top news
A new teacher has been hailed a hero after she intervened when a student opened fire in a school killing a girl and injuring four others.
The public love him but The X Factor judges seem shocked the Essex crooner has lasted three weeks on the live shows.
Rumours are swirling comedian Russell Brand is considering running for Boris Johnson's job.