By Sophie Pierce
BBC News, Devon
An office block on a Devon industrial estate is not the most likely place to find detectives at the forefront of tackling internet-related paedophile crime.
The team has between 20 and 30 new cases coming in every month
But this is the home of Devon and Cornwall Police's Force Online Investigation team, which has seen a huge increase in its workload.
Det Insp Simon Snell, who heads the unit, says the number of paedophiles using the internet to target and abuse children is still growing worryingly.
"We dealt with 250 cases last year, and we have between 20 and 30 new cases coming in every month," he said.
"To put it in perspective, the amount of illegal material stored on our server has increased twelvefold in the last three years - from 5,000 gigabytes in 2005 to 60,000 in 2007.
"We currently have 5.5m indecent images on it relating to numerous investigations."
Paedophiles use the internet not just to view images, but to distribute them and network with other offenders.
The growth of social networking sites has led to "grooming" - where offenders make contact with children online with a view to meeting up with them in the real world.
Det Insp Snell thinks this is a particularly worrying development.
A screen tells investigators how much space is left on the server
"This is significantly concerning us at the moment," he said.
"We have had cases where children have given out their names and addresses and other personal details, enabling the paedophile to track them down and make contact.
"We even had one case at a Devon school where five pupils were all in contact with the same person, who they didn't realise was a paedophile."
The Force Online Investigation Unit has a team of specially trained civilians, called digital evidence investigators, working alongside detectives.
When an offender's computer is seized it is brought to a secure area known as the Acquisitions Room.
Steve Slater, manager of the separate High Tech Crime Unit, which works with the Force Online Investigation team in dealing with paedophile cases, says great care has to be taken as the evidence has to stand up in court.
"We physically examine the computers here, photograph them and remove the hard drive," said Mr Slater.
"We then take a forensic copy of the suspect's drive and then store it to our systems."
When an offender's computer is seized it is brought to a secure area
Once the computer has been dealt with, the digital evidence investigators have to go through the images to determine their severity; they categorise them on a scale of one to five.
There is no alternative to looking at the images - a distressing task.
However, once an image has been categorised, it does not have to be viewed again, as one of the investigators, Nick Tallamy explained.
"A digital fingerprint is made of the image, so if it re-occurs then we don't actually have to re-examine it," he said.
The managers of the unit are acutely aware of the impact on staff of having to look at images of children being abused.
Everyone has mandatory counselling every six months, and if someone feels they cannot deal with a particular issue then they can walk away from it.
Det Insp Snell says it is a very challenging area of police work, but he finds focussing on the end result helps.
"I think what keeps you sane is that it's really rewarding to take kids away from abusive situations, to prevent abuse happening.
"Yes, it is distressing, some of the images we have to look at are horrendous, but if you find that's no longer a problem for you, then it's time to get out."