By Mike McCarthy, North of England Correspondent
New measures to protect victims of domestic abuse come into effect today.
Clare's Law, which enables people to check the police records of partners, has been launched across England and Wales after being piloted by four police forces.
The father of murder victim Clare Wood, whose name has been given to the scheme, has welcomed its introduction, describing it as "a bittersweet moment".
Clare's killer George Appleton
Michael Brown discovered five years ago that his daughter had been raped and strangled at her Salford home by ex-boyfriend George Appleton, who set fire to her body before going on the run. He was found hanged several days later.
Appleton, who Clare met on Facebook, had a history of violence against women, including knife-point kidnapping.
Mr Brown told Sky News: "When you lose a family member in these circumstances it is always with you. To realise that the last moments of your daughter's life were kicking and screaming in a room in Salford sticks with you."
The 70-year-old said Clare's Law was "not a panacea for domestic violence" but added: "If it can help others - just one - I and all the other campaigners will have succeeded.
"This is just another piece of armour plate for people to put on when they are in trouble."
The launch coincides with International Women's Day and also marks the introduction of Domestic Violence Protection Orders (DVPOs), which are designed to provide support for victims in the immediate aftermath of violent incidents.
Michael Brown has fought for a new law to help women like his daughter
DVPOs can last for up to 28 days, during which time a perpetrator can be prevented from having contact with the victim.
Speaking about Clare's Law, Home Secretary Theresa May said: "What we saw from the pilots was a real benefit for women who were able to go to the police where they had suspicions about the behaviour of their partner.
"As a result of that, they were able to make a decision about whether to stay with that partner or to leave."
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