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How Forged Documents Are Detected: Paper, Ink, Typewriters and Signatures

The plain-English version of what a questioned-documents examiner looks at, from watermarks to signature tremor.

By Anchit Tandon, updated 26 October 2026

A questioned-documents examiner is the person a court calls when a will, deed, cheque or letter might be forged. The work is less about magnifying glasses and more about one simple idea: every material has a history, and a forger has to get all of it right at once. Here is what examiners look at, in plain English.

1. The paper

• Watermarks. A watermark is pressed into paper while it is being made. Mills changed their marks and designs over the years, so a watermark can show the earliest date a sheet could have existed. A deed dated 1948 on paper whose mark was first used in 1961 cannot be genuine.
• Fibre. Older fine papers were often made from cotton or linen rag. Cheaper modern papers are mostly wood pulp. Under magnification the fibres look different.
• Glow under ultraviolet light. Many papers made from the mid twentieth century onward contain optical brighteners that glow blue-white under UV light. An "old" document that glows brightly deserves a closer look.
• Artificial ageing. Tea, coffee, heat and rubbed edges can make paper look old to the eye, but the staining usually sits on the surface and does not match genuine slow ageing.

2. The ink

• Type of pen. Fountain pen, ballpoint, gel and felt-tip inks leave different line shapes. Ballpoint pens only became common after the Second World War, so a ballpoint signature on a document dated much earlier is a warning sign.
• Different inks on one page. Under different wavelengths of light, two inks that look identical to the eye can behave differently. That is how added words and changed numbers are often found.

3. Typewriters and printers

• Every typewriter wears in its own way. Letters drift out of line, serifs break and some keys strike harder than others. Those defects act like a fingerprint for one machine.
• Typefaces were designed and sold in particular years, so a typeface that did not exist yet on the document date is a strong clue.
• Carbon copies and certain single-use ribbons can keep a readable record of what was typed.

4. Signatures and handwriting

• A genuine signature is written fast, from habit, with smooth strokes and tapered starts and ends.
• A copied signature is usually drawn slowly. Look for shaky lines (tremor), blunt starts and stops, pen lifts in odd places and retouching.
• Examiners compare the questioned signature with many genuine samples written around the same date, because everyone's signature varies a little.

5. Indentations, stamps and seals

• Writing on one sheet can leave invisible dents on the sheet underneath. Special lighting and electrostatic equipment can reveal them, sometimes exposing a draft or a practice signature.
• Revenue stamps, stamp paper and seals were issued in particular designs and values at particular times. A stamp issued after the date on the document gives the game away.

Does a court accept this evidence in India?

Yes. Under Section 39 of the Bharatiya Sakshya Adhiniyam, 2023, which replaced Section 45 of the Indian Evidence Act, the opinions of experts on questions such as the identity of handwriting are relevant facts. The court still decides what weight to give an expert's opinion.

This guide is a general introduction. Real examinations need trained examiners, original documents and proper equipment.

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