A subtle detail on a bedroom wall helped investigators identify and rescue a young girl who suffered years of abuse after images of her were circulated on the dark web, according to a new investigation.

The case was handled by Greg Squire, a specialist online investigator with US Department of Homeland Security, who works to identify children appearing in online abuse material.

Investigators initially had very little to work with. Images shared on encrypted dark web platforms were deliberately cropped or altered to remove identifying features, making it nearly impossible to determine who the girl was or where she lived.

According to Squire, the breakthrough came not through advanced technology but careful observation. Investigators closely analysed everyday objects visible in the images, including furniture and fixtures, to narrow down the possible location to parts of North America.

The key lead emerged when experts identified a distinctive type of brick visible on a bedroom wall. A brick specialist recognised it as a product manufactured and sold only in a limited region decades earlier. Because bricks are rarely transported long distances, the information significantly reduced the search area.

By combining this clue with other consumer data, investigators narrowed the list of possible addresses and eventually identified a household where the girl was living with a convicted sex offender. Local authorities moved quickly, arresting the suspect and ending years of abuse. He was later sentenced to a lengthy prison term.

The investigation is featured in a long-term project by BBC World Service, which followed specialist units across several countries to show how child exploitation cases are often solved through painstaking analysis rather than sophisticated tools.

Investigators involved said the case highlights both the complexity of online abuse investigations and the emotional toll such work can take. Squire acknowledged that prolonged exposure to disturbing material affected his personal life, prompting him to seek professional help.

The rescued victim, now an adult, later met Squire and said sustained support had helped her rebuild her life. Investigators say the case underlines the importance of international cooperation, specialist expertise and persistence in protecting children from online abuse.

Authorities continue to urge technology companies and the public to cooperate fully with law enforcement efforts aimed at identifying and safeguarding victims.

With inputs from BBC