A RED line on a map plots the route of one of Hull's most prolific criminals.
Joined by yellow dots, it snakes up Marfleet Lane before stopping in east Hull.
"That's his grandma's house," says Detective Constable Karl Palmer.
The offender has been wearing a new electronic tag, which allow his movements to be tracked by satellite, for a few hours.
With one click of a mouse, police can see where he is 24 hours a day.
"He's probably gone to show his grandma the tag and what it does," says DC Palmer.
As part of a trial being run by Humberside Police, some of the region's high-risk sex offenders and most prolific criminals are having their movements permanently monitored.
The tags can even alert police if a sex offenders goes near a school or park, or if a serial thief enters a shopping centre.
Although police have no legal powers to force them to be tagged, criminals are queuing up for their turn.
"At first we thought we wouldn't get them on people, but we have had huge demand," says Detective Inspector Darren Webb, who has led the trial.
"We have them coming to us now, asking to wear it, because they have seen how it helps other people."
Next to him is a computer showing the movements of the current tag wearer. A quick click of the mouse shows how you can create "exclusion zones", which mean police receive a text message if the wearer enters them.
Beneath the map, which shows his recent movements, is a list of the times the tag has "pinged". The tags use GPS technology to send a location signal at least every two minutes.
The screen also shows the speed he is travelling at, the battery level of the tag and whether it is strapped to the ankle.
"The software that comes with it allows us to see so much detail," says Det Insp Webb.
"The more we are using it, the more efficient and effective it is becoming."
A map showing where the wearer has been can also be placed over a map of recent crimes, allowing detectives to quickly see if they are suspects.
"If they were in the area at the time, it doesn't necessarily mean they have done it, but it is a good starting point," says Det Insp Webb.
"It could be enough to arrest them or it could just allow us to start building a case and looking for other evidence, like CCTV."
So far, five of Hull's most prolific criminals – known as gold offenders – have worn the tag. There is also a tag in the East Riding and another for sex offenders managed by Multi Agency Public Protection Arrangements.
Although the force only has six tags as part of the trial, officers say it has already reduced offending and saved money.
One man, Glen Foster, wore the tag for five weeks. It showed he was in Wellesley Avenue, west Hull, when a man was seen looking into cars.
He was found to have three keys from corned beef tins, three torches, black gloves, pliers, a screwdriver and scissors and was jailed for a year for going equipped to steal.
The Honorary Recorder of Hull and the East Riding, Judge Michael Mettyear, said the case showed "success for this new innovation".
One criminal, who has worn the tag and does not wish to be named, says: "I knew it would help me stay out of trouble and show the police that I wasn't doing anything wrong.
"I didn't want to take it off because I knew, without that stopping me, I would re-offend straight away and go back to prison."
A review of the first three months of the scheme written by Det Insp Webb recommends the force buys 20 more tags, which cost £200 a month.
He compares this to the average cost of £40,000 to imprison someone for a year, which doesn't include the financial impact of their crimes on society.
"That £40,000 will be a fraction of the true cost of these people committing crime," he says.
"When you consider that a tag costs £2,400 a year, it seems like a no-brainer. That doesn't take into account the impact crime has on the victims and, ultimately, this is about preventing crime.
"If we can stop these people committing crimes, we will have a safer city. It saves money and time compared to traditional methods of policing, such as following and watching these people.
"This technology is definitely the future."
