The LORD OF THE RINGS star was so taken by the reporter's tale that she felt "enormous responsibility" towards Veronica's family in how the movie - also called VERONICA GUERIN - portrayed her life.
Veronica was murdered in 1996 after penning a handful of exposes on Dublin's underworld crime lords and drug dealers for Ireland's SUNDAY INDEPENDENT newspaper.
Three men were accused of her murder, two of whom are now in prison for the crime.
The third, JOHN GILLIGAN, was acquitted but sentenced to 28 days in jail on drug charges - he is currently appealing this decision in Dublin's High Court.
Cate, 34, says, "It's very powerful - especially with Gilligan back on the stand, it's not gone away."