How can an app help domestic abuse victims?

Evidence is crucial when prosecuting domestic violence, but often survivors and witnesses find it difficult to remember exact dates and incidents of abuse. The Cithrah Foundation, a domestic violence refuge based in Northern Ireland, has addressed this problem with the development of an app which has been funded by Comic Relief. The app anonymously builds up a body of evidence that can be used to prosecute the perpetrators of domestic violence. Woman's Hour's Jenni Murray speaks to Liz Gibbons who devised the app and to Catherine Harper, the founder of Cithrah.