0220 GMT January 17, 2019
Officers found the trio while searching an address in Belper in Derbyshire, England, on Monday, derbytelegraph.co.uk reported.
They originally found four people and subjected all of them to fingerprint checks with their new mobile biometrics device.
The checks revealed that two of the four had illegally absconded and were in the UK unlawfully, and were detained.
A third person was also detained after no fingerprint result was found for him.
Further investigation revealed that the man had entered the UK illegally three to five months ago in the back of a lorry.
The fourth person’s identify was proven with their fingerprints and so was not detained.
Derbyshire police’s mobile data team originally released this information via Twitter.
The team said in the tweet: "His detention would have normally been necessary to prove his ID so once again it shows that #MobileBiometrics isn't always about looking for an arrest.
“Staff from the team said that this kit is meaning that they have to detain people for less time and is reducing arrests."
The new kit was rolled out in mid-October. A total of 250 devices were handed out to frontline officers and specialist departments.
They allow officers to check fingerprints against criminal and immigration records on patrol by connecting them to two databases — IDENT1 and IABS.
Hardyal Dhindsa, Derbyshire’s police and crime commissioner, said, “It’s so important that we take advantage of the benefits of new technology to help officers spend more time out on the beat instead of losing time coming back to the police station.
"That’s why my budget this year allowed for investment in the most up to date technology and I’m pleased to see that it is clearly proving itself very useful and effective.
“Technology is helping to make police officers more visible on our streets which is what people tell me they want to see and undoubtedly it has operational benefits too.”
When the scanners were rolled out initially, Assistant Chief Constable Bill McWilliam saidm “These devices are live in a number of forces across the country and are proving to be very beneficial.
“Mobile scanning of fingerprints will prevent officers having to make unnecessary trips to police stations, therefore saving valuable time to allow them to continue with their work whilst out and about.
“This technology can only be used where an offence (or suspected offence) has been committed and where identity is doubted. Officers will not be conducting extra stops as a result of having this device."