HSA's Novel Forensics Approach Exposes Doctored Documents

To the untrained eye, the document looked like it was created before 2015 and appeared to show a series of industrial designs made and dated before that year.

- David Sun

The PDF file was submitted as evidence by one of the parties in a dispute over the ownership of a proprietary design in 2022.

But a novel approach to forensics by scientists from the Health Sciences Authority (HSA) quickly uncovered that the document had been doctored and was actually created after 2015 because the font used did not exist before 2015.

Such materials with disputed legitimacy are referred to as questioned documents, and are typically treated using traditional methods, where elements such as handwriting and signatures are examined.

But since 2020, HSA's Forensic Chemistry and Physics Lab has been pioneering a joint approach that uses both the traditional methods and analysis of the document's metadata.

This means that aside from scrutinising traditional elements such as handwriting, it also checks the file data down to each byte.

Mr Louis Koh, a senior forensic scientist at HSA, said the lab discovered a font file in the doctored PDF document by analysing the file's data streams.

He said: "Data streams are like packets of information inside a file. If you extract these streams, initially they may not be readable by humans.