When former police detective Kris French joined Norfolk Constabulary in 2002 he was driven by his desire to do good for the community and lock bad people away.
But after a harrowing child abuse case, he left the force to teach children how to fight back.
The 40-year-old, from Attleborough, joined Norfolk's child abuse unit because he thought it would enable him to help children and put away offenders.
He was able to do that, but after 16 years, the father-of-two was left emotionally scarred and questioning his career after witnessing the horrific abuse vulnerable children had faced.
Now Mr French has swapped his badge for a black belt by becoming a full-time martial arts instructor, teaching self-defence to youngsters in a bid to prevent them from becoming victims.
Mr French, who runs the Kuk Sool Won martial arts school at Thetford Grammar, said: "When I joined the child abuse unit, I felt really passionate about it, I thought I could help.
"I was naturally very good at engaging with the children because you need to have a very open manner for a child to meet you for the first time and tell you about the worst thing that has ever happened to them.
"But it was after my first child was born in 2015 that I took a bit of a turn and it started to upset me more."
Now a fifth degree black belt, 'Master Kris French' has been a Korean martial arts instructor for most of his life and while working as detective in 2013 he started his own Kuk Sool Won school.
But after the birth of his first child, and switching between child abuse cases in the day to teaching children martial arts at night, it started taking its toll on his mental health.
He said: "I was moved to the sex-offender management unit, to monitor offenders post-conviction to stop them re-offending.
"You have to engage with them find out what makes them tick and talk about every aspect of their offending.
"It was extremely difficult to speak to someone while they are describing what they are sexually attracted to, and they are essentially describing your child."
But it was one child abuse case in particular which made Mr French question the work he was doing, and although he was helping to get offenders sent to prison, the damage had already been done to their victims.
"An offender had abused his two step-daughters for years and was sentenced to 18 years in prison," said Mr French.
"Neither one knew the other was being abused. He told them that if they refused him or told anyone he would use her sister instead. So they both suffered for years thinking they were protecting each other.
"I was there throughout the court hearing, but as the sentenced was passed I looked across at the two girls, not far from becoming adults, and thought it simply wasn't good enough.
"It didn't take away the pain and agony of all that they had suffered. I thought what if they would have had the skills to protect themselves, or the confidence to speak out, if that would have stopped it from happening."
It was then when Mr French decided it was time to take a career break from the police to focus on his martial arts school.
Mr French said: "I couldn't do it anymore. I was teaching classes in the evenings having just literally picked myself up from my bedroom floor crying my eyes out but I had to tie the belt and get on with it.
"I had a complete meltdown, not only could I not do my job but I couldn't function in day-to-day life. So I went to the doctors and said I needed help."
After working part-time jobs while running his Kuk Sool Won School in the evenings, Mr French has decided he will not return to the force, and has officially handed in his resignation and says he will now work full-time teaching martial arts.
"I thought I could make a bigger difference elsewhere," said Mr French.
"What I teach gives children techniques to use if they feel in danger or it trouble.
"I love what I do and I only wish I had done it sooner. My students are confident, respectful and decent members of the community that will not become victims."
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