All 43 police forces in England and Wales have signed up to the latest version of the system for significant criminal investigations, dubbed 'HOLMES', short for the 'Home Office Large Major Enquiry System'.
Unisys is responsible for delivering the third major update to the system, which it won a contract to run in 1996.
The launch of 'HOLMES 3' represents the first procurement of a national policing system using the G-Cloud framework, according to the US IT giant. Each individual police force signed a separate contract for the system, which includes new functions such as GIS mapping and visualisation.
The system gives senior officers a "real time view of live operations" to help them decide how best to deploy police resources, Unisys said.
Police hope that it will help them to collaborate across forces and other agencies during investigations and find previously hidden links between cases.
'HOLMES 3' will be delivered through a single browser-based application hosted in a single private cloud.
Unisys said that is has improved functionality for tasking, alerting, reporting, messaging, document management and analytics, and has automated "many of the processes which were previously manual".
The system is based on the Unisys 'Law Enforcement Applications Framework' launched in June. Its listing on the Digital Marketplace (until recently the G-Cloud catalogue 'CloudStore') says that it costs about £840 per user per year.
Unisys did not disclose the value of the deal but said it expects savings "will run into many millions" over the duration of the two year contract.
Durham Constabulary's chief constable Mike Barton said that the improved functionality of the system will help to reduce the number of police systems, in accordance with national policy.
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