West Yorkshire Police's retiring chief constable has said the murder of MP Jo Cox was the most difficult thing she had to deal with during her career.
Dee Collins recalled that "having to tell the world what had happened" to Mrs Cox had a "huge personal impact".
The 41-year-old Labour MP for Batley and Spen was killed in 2016 by right-wing extremist Thomas Mair in Birstall.
Ms Collins, the force's most senior officer, will step down on Tuesday because of health challenges.
The chief constable, originally from Lymm in Cheshire, has served 31 years in policing, 12 of those as assistant chief constable of Derbyshire Constabulary and then as chief officer of West Yorkshire.
She underwent surgery and radiotherapy after finding a lump in her left breast in 2009, but shared her story to try to encourage others to check themselves.
Reflecting on her career, Ms Collins said the most difficult times were when the force got things wrong or let people down.
She said: "Without a doubt the most difficult thing for me was the murder of Jo Cox.
"I have to say I have the most upmost admiration for people who put themselves in the positions that Jo did in terms of standing up for the public, trying to ensure that her local community was cared about an looked after."
Ms Collins said her biggest frustration was leading a stretched organisation that could not deliver the services the public deserved.
She said "day to day crime" was not being investigated thoroughly because there weren't "enough officers to go around to deal with everything".
Recalling her highlights, Ms Collins said she was proud of the work she had done around inclusion and hoped it inspired other women to take up senior roles in policing.