Nasty things with nice ending
My dad was a copper in the 70s and 80s. As a lot of the stories here have already attested, things were done differently then – for better or worse. I've heard a myriad of anecdotes from him demonstrating behaviour that was ethically and legally dubious, and like most coppers of that era he has no regrets.

One time though, I got a glimpse of how his job could sometimes bring something good out of something awful.

We were in our local pub several years after his retirement from the force, stood at the bar having a quiet pint. I'd clocked a 30-something lady sat in the corner of the bar with some other people, and she kept casting curious glances our way. I presumed it was because we're such a smashingly handsome pair of drunks. After ten minutes of this shy staring, something seemed to click in her. She got up, walked straight over to the bar, said hi to my dad, and to my surprise hugged him and burst into tears. He cuddled her and gently led her to a quieter spot of the pub.
I watched from the bar as my dad spoke to her for a couple of minutes. Couldn't hear what they were saying, but he seemed to be reassuring her. She alternated between smiles and tears, and after another hug and a 'good to see you' my dad came back over and told me the story.

When the woman was a little girl, she'd been regularly raped by her dad. He'd also raped her sisters and mum too. Naturally this was accompanied by savage kickings. The family occasionally came to the attention of the police, but the girls were always too scared to testify against the man.
After years of beatings and rapes, one day this bloke went too far and attacked their mother so violently she bled to death. He was quickly locked up and charged, but seemed smugly confident that he'd get off lightly.
My dad was the senior investigating officer on the murder case, and soon uncovered the history of unthinkable abuse that everyone knew about but no-one would talk about – they even found a written record from the dead mother, outlining every hateful thing this fella had done to her and her children. It took a long time to get the girls' trust, but my dad eventually convinced them that if they told the truth, he'd make sure the man would never hurt them again. They believed him, and agreed to do it. With their statements he was able to put together an airtight prosecution file (this was before the CPS). Their father was put away for life, and died in prison some ten years later.

Everything was done by the book – no forced confessions, prisoner abuse, lying or perjuring, nothing that would jeopardise the integrity of the investigation, despite everyone on the team having an understandable loathing of the suspect. Ultimately, the case hinged on my dad making a promise to some terrified little girls and being able to keep it.

He's alright, my dad.

By way of compensation for lack of lulz, have some classic internet:
www.youtube.com/watch?v=Sahm3ot89cc
( Wet-chinned bag shanker Cannot parse Wogan, Tue 10 May 2011, 13:41, 2 replies)

Your dad's more than alright - he's put a lump in my throat.
This also seems to definitively answer the debate about cops breaking the law in order to secure convictions (although I'm surprised not to have seen more mention of famous miscarriages like Derek Bentley or Birmingham 6 in that context). All this plus crimlols at the end!
P.S. click
(sarcastic fringehead feet of clay, buns of steel, head of lettuce, Tue 10 May 2011, 17:41, closed)

Ah, v. kind of you to say so.

( Wet-chinned bag shanker Cannot parse Wogan, Tue 10 May 2011, 19:48, closed)