A cutting-edge analytical tool developed by researchers at the University of Sheffield is helping police forces across the UK identify and protect potential victims of human trafficking and sexual exploitation.

The Sexual Trafficking Identification Matrix (STIM), created by Dr Xavier L’Hoiry in collaboration with international partners, is designed to assess online adverts posted on adult service websites.

By analysing elements such as photographs, language, and descriptive details, STIM generates a risk rating—low, medium, or high—that helps law enforcement and support organisations determine whether further investigation or victim support is needed.

Thames Valley Police has been at the forefront of implementing the tool in the UK. Detective Chief Inspector Ben Henley, who leads the STIM project within the force, said the technology has transformed their approach.

“We were previously reliant on victims coming forward, which was unfortunately very rare,” Henley explained. “STIM has helped us proactively identify those at greatest risk and respond more quickly.”

Since adopting STIM, Thames Valley Police has scored over 128 online adverts, leading to 40 site visits and safeguarding dozens of individuals. The force currently has five active criminal investigations and has made multiple arrests linked to STIM assessments. Henley added that other police forces have reached out to replicate the model, and the tool has now been recognised as national best practice.

One of the major challenges in combating trafficking is distinguishing between legitimate sex worker profiles and those created by traffickers. STIM aims to streamline this process, reducing the burden on investigators who previously had to manually sift through thousands of adverts.

Dr L’Hoiry, from the University of Sheffield’s School of Sociological Studies, Politics and International Relations, worked with partners including the Universities of Northumbria and Copenhagen, law enforcement agencies, and NGOs such as the Danish Centre Against Human Trafficking (CMM).

He said the tool addresses a growing concern in the digital age: “Traffickers are increasingly using adult service websites to reach more customers while evading detection. STIM helps practitioners intervene more efficiently and effectively.”

To date, STIM has been adopted by 16 UK police forces, two charities, four international police forces, and CMM in Denmark. The development team has delivered 30 training sessions to over 100 police representatives, and continues to refine the tool based on user feedback.

“Our goal is for every UK police force—and organisations worldwide—to use STIM to identify victims and develop meaningful interventions,” said Dr L’Hoiry. “This is about taking academic research beyond the university and into the hands of those making a real difference.”