‘I was in the Met for 34 years, police need to look internally to stop corruption’

• Howard Groves is a retired Detective Chief Inspector who worked with the Metropolitan police for 34 years, and was in charge of one of London's murder units for three decades.

• Cops Gone Bad premieres on Crime+Investigation at 9pm on Monday 26 February and will be available to stream on Crime+Investigation Play

Being an ex police officer, I think it's only right the public has a better understanding of some of the issues that the force faces, but the police also have to demonstrate that they are dealing with their own bad apples.

Those individuals who join the force probably had the greatest of intentions, but for some reason — perhaps because they have power they've never had before, and felt that they knew how the system works— thought that they could get away with these crimes.

It's not just murders and rapes, you can think of any other crime that normal Joe Public would commit —police officers are committing it, and that is a worrying trend.

The hierarchy within the police service up and down the country must look internally at their processes and their practises, recruitment, retention to stop police corruption from happening.

We are examining past cases of corruption in Cops Gone Bad to highlight some of the issues that the police service would have to deal with if they want to gain back the confidence of the public. By highlighting these cases, I hope it may also allow officers within the police service to feel that they can have a better opportunity to raise a head above the parapet and say 'look, I've got an issue with a colleague'.

They may worry they've got the wrong end of the stick but they should feel confident that they can go to someone who will at least look into the matter without feeling 'well if I do that, I'm gonna get ostracised so I'm just gonna keep quiet'. Because I'm sure there are lots of officers up and down the country now who have fallen into that category where if they'd said something earlier on they may have dealt with officers who were bad apples earlier.

I was a member of the Met for 34 years, 30 years of that was as a detective in charge of one of the murder teams in London, and when I was a young detective Rodney Whitchelo was a Sergeant. So, unfortunately, I can say I've got first hand knowledge of being disappointed with somebody who, I would say, betrayed the badge.

He contaminated jars of baby food, but even though I think 'why? how could he even think about trying to poison children and creating mayhem?', I've come to realise it's only the individual who can answer the question as to why he decided to commit such a heinous crime.

When I was on the force I would be investigating murders, attempted murders, as well as other crimes that the hierarchy deemed of public interest so I'd like to think that I've had a varied career. Thanks to my experience, I can easily work through the whole investigative process — the when, where, what, why, who. That's what it's all about as far as investigating is concerned, and that's how I wanted to approach things on Cops Gone Bad.

As the investigator, it's much more about getting to the crux of why somebody committed a particular crime. Was it, if you talk about murder, a relationship between two parties or a stranger attack? And then you have to put together your team of officers, in terms of who's going to look at CCTV, who's going to look at phone data, and all the things that police bring to bear in order to establish the facts for a particular case.

Each of these cases that we've dealt with on the docu-series follow a similar pattern in terms of the investigative process, but there's more to this programme than just that. It is a realisation for the public that police officers are a representation of society.

The bad cops we've looked at have certain things about them that means being in a position of power, and having the control of a badge, makes them do things that they would not normally have done. That doesn't mean that they joined with that intention, but once they get into the police service then they abuse that power.

By making a show like Cops Gone Bad, I hope that the public in the first instance will see they have the opportunity to say to the hierarchy, 'sort yourself out, and until you do so we will have no confidence and trust in you'. So the hierarchy therefore have to put measures in place to demonstrate that they are trying to deal with it, and I believe over time we will see more officers, unfortunately, who will have to be dealt with.

It's a fine balancing act between giving those officers and members of the public the confidence to come forward, and at the same time demonstrating that you're dealing with these bad apples. I know it will take time before the police gain the public's confidence.

Howard told his story to Roxy Simons.

Cops Gone Bad premieres on Crime+Investigation at 9pm on Monday 26 February and will be available to stream on Crime+Investigation Play.

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Watch the trailer for Cops Gone Bad: