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07/01/2006

Watching You, Catching You, Locking You Up?



20% of the world's CCTV cameras are to be found in the UK. The existence of CCTV footage is now an integral part of any criminal investigation. Any police officer reporting a crime is required to establish whether there are cameras positioned locally, and whether any footage has been recorded.

CCTV tapes are seized on a regular basis, whether or not they contain anything useful. The vast majority of footage is recorded in time-lapse in a multiplex format. This means that one tape will often contain footage from a large number of cameras. This footage will not be 'live time' unless an incident has been specifically filmed by the operator.

This causes a number of problems. Criminal incidents, by their very nature, often happen quickly. Footage in time lapse, assuming the camera was pointing the right way, more often than not merely shows 'snap shots' of the incident concerned. Figures can be seen from a distance doing 'something'. This footage will show that some kind of offence has taken place. It is more than useless for the purposes of finding out who did it.

Identification of the suspect is a key part of criminal law. The prosecution is required to prove that a crime has been committed, and that the person charged was the person who did so. Identification is therefore a complex area. As can be seen above, unless an incident has been filmed live, identification is rarely assisted by CCTV.

Live time CCTV footage often provides compelling evidence. This is very useful should the suspect have been arrested. If not, you are left with the footage to work with. This relies on the line of sight being clear, and the facial features of the suspect being seen. This can often be frustrated by head or facial coverings, and more commonly, the suspect not looking in the direction of the camera. Even if there is good footage of the face, this person still needs to be identified. Pictures are often circulated in police publications with very little success.

CCTV viewing occupies a dis-proportionate amount of police time with very little tangible result. This fact is well known to street criminals. The deterrent effect, as with any negative, is very difficult to gauge. Taking account of this, the question must be asked - Are the powers that be justified in deploying so many CCTV cameras?

11 comments:

John said...

Judging from the discussions that went on when our local scheme was being discussed, the general public think they are the be all and save all of modern times. Police offering a rational line in accord with your blog stood no chance against the carefully-prepared demo video from suppliers. So, now we are to spend £X,000 to check on kids buying fags under-age. There is no other crime on our streets. One would think that seeing Crimewatch would reveal the truth in these con items. Still, thank God they have not found a way to fine us if we walk past one too fast!

Universal Soldier said...

Don't they have some kind of deterrent effect - or is that just another myth we are labouring under?

Bystander said...

The few occasions when CCTV shown in court has been of any use were mostly to do with fly-tipping and the like, and cameras were operated by a human. Marks & Spencer's systems are first class (37 cameras in my local store - all hi-res colour). Of course that doesn't account for the times when the offender sees the tape and puts his hands up for a plea discount.

SteveG said...

The CCTV footage we see in the Crown Court where I work is usually pretty hopeless for identifying people; only the other week, someone was acquitted of a pretty serious offence after (I assume) the jury felt they couldn't be sure after watching the main evidence that the chap who'd been filmed for over an hour by a CCTV camera in a quite, well-lit pub playing pool for over an hour was the defendant. I wasn't sure, either; it certainly showed a slim, white male in his 20s with short dark hair, about 5'8" wearing a dark Adidas jacket and jeans, which the defendant certainly possessed, but that description would fit a lot of pool players in most big cities and the jury were asked 'are you sure that's him?' (sure enough to see him go down for several years, at least) rather than 'do you think that's probably him?', which, IMO, it very probably was.

They can, though, be very useful in court when there's no argument about who they show, even though you might not recognise the people without independent confirmation. I can think of at least two examples over recent months where CCTV footage has provided pretty convincing evidence not of people's identity, which wasn't in dispute, but of who attacked whom and what happened next.

Anonymous said...

Are there any high-tech solutions to this? Rather than having a officer waste hours viewing tapes, couldn't a computer with suitable face-recognition software at least identify the relevant bits of tape? Perhaps I'm being optimistic here.

World Weary Detective said...

Steveg, I agree that CCTV can often provide a compelling visual narrative. This is an area that CCTV comes into its own, and has often led to early guilty pleas therefore saving the public money. The huge difference is whether the suspect has been identified without the use of the footage. Disputes over ID on CCTV are massively complex.
Facial recognition has been used, but appears to have fallen by the wayside. This software was, I believe, based on a database of 'known' faces. Should these individuals be spotted, the computer system alerted the operator. I don't think there is software available that can identifty suspects any other way. I would be interested if anyone knows differently?

Steveg said...

The technology is changing all the time, but as far as I know, facial recognition technology isn't really suitable for these purposes.

'Supporters of biometrics draw a distinction between face-recognition surveillance of a moving crowd and use of the technology with a single, stationary subject in a setting where the lighting is controlled.

"It's a problem if you use it in a part of the airport where people are on the move and there's different lighting in different areas," said Bill Willis, senior vice president for technology at ImageWare Systems, a San Diego imaging and biometrics company.

"With a stationary subject, under controlled lighting, where you're comparing one face to a database, it works 100 percent of the time." '

http://www.signonsandiego.com/news/computing/personaltech/20030929-9999_mz1b29biomet.html

While facial recognition technology may well be useful for, for example, helping ensure that someone can only enter a secure area of an airport if his face is on the database of employees authorised to be there, it's apparently not much use for scanning the concourses in search of people on a watch list because you get so many false positives.

World Weary Detective said...

I think that clarifies matters. I'm sure it's being worked on. Must be a lucrative contract waiting to happen!

Steveg said...

Part of the problem, I think, is that sales reps are pushing at an open door when they come round selling security technology to politicians. The politicians are anxious to be pursuaded that there actually is a magic fix available to solve problems and like to be able to announce they've 'invested' pots of money in a sure-fire solution to whatever's bothering them.

A couple of years later, when the sure-fire fix turns out to be anything but, the minister will probably be in a new job, or there'll be a newer and better magic gadget available, or clearly we need another Criminal Justice Act....

Bruce Schneier, one of the top US security gurus, is well worth reading on this at http://www.schneier.com/.
He's very sceptical about hi-tech fixes, as opposed to intelligent use of technology, and repeatedly makes the point that the best investment government can make if it wants to fight crime and terrorism is in having plenty of skilled and experienced police officers using their professional judgement.

Anonymous said...

Can I tell you a sad and sorry tale? I should be doing a Crown Court bill but wander the internet looking for things of interest to avoid doing what I should be doing. It's just like avoiding the ironing really.
Anyway, went to the police station to deal with regular client who had been arrested for a theft from motor vehicle.
Eventually prevailed on officers to show me the CCTV. It was absolutely damning. The police had a fantastic programme on which one could slow each image down and have an enhanced view. It clearly showed my client on LHS of screen walking past car, going back, and then running off with property from car.
I advised my client to make no comment on the basis that he had no defence and anything he did say would make it worse.
As regularly happens, having been bailed the client did not fancy an immediate custodial and when the case came to court would not enter a guilty plea despite my (at the time) best advice. He indicated not guilty.
Time passes, at pre-trial review stage the CPS serve me with CCTV evidence. I watch the CCTV to remind myself of case - of course because months have passed I have forgotten exact details of the case. I even check my notes from police station.
I am gobsmacked to discover that the whole of LHS of screen has not been copied. They have lost all the evidence.
At trial client found not guilty.
Joined up justice - don't make me laugh.
Before any one complains about my conduct;
I did my job to the best of my ability. I advised the client correctly at the police station and at court.
The defence cannot be blamed for the failings of the prosecution.
In any event this must happen time and time again and all it shows is that human failings plays a greater part in the criminal justice system than Tony Blair would have you believe.
Of course if he allowed the Magistrates Court tohave the same systems for watching CCTV as the police this sort of thing would not happen again

World Weary Detective said...

Lost evidence is an unfortunate result of the monolithic systems and organisations we have. Better the gulity walk free through incompetence that the innocent be convicted. Thanks for your comment.