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Google's Timeline feature is set to be used by police in the US to track the movement of criminalsReuters

Law enforcement agencies are exploring the applications of Google's Timeline for tracking the exact movements of suspects, according to a report being shared with police forces in the US. The Timeline feature has recently been expanded to allow users to view their movements, potentially over the course of years, on a map.

The report, obtained by The Intercept, is titled Google Timelines: Location Investigations Involving Android Devices. In it, the usefulness of Timelines is outlined to investigators by law enforcement trainer Aaron Edens.

"The personal privacy implications are pretty clear but so are the law enforcement applications," the report states. "It is now possible to submit a legal demand to Google for location history greater than six months old. This could revitalise cold cases and potentially help solve active investigations."

Edens, an expert in mobile phone investigations, revealed in the 15-page report that his own location data dating back to 2009 was being stored by Google. Details of his specific longitudinal and latitudinal position were recorded by his Android smartphone.

The report recognises the weaknesses of Timeline as a comprehensive tracking feature, most notably the fact that users can delete location data or turn the feature off entirely.

Google does not publicly specify what requests are made by law enforcement agencies, however the firm's transparency report reveals more than 20,000 requests were made in 2014. Google said in a statement: "We respond to valid legal requests and have a long track record of advocating on behalf of our users."