Forensics: Handwriting analysis

No Trace Project > Threat Library > Techniques > Forensics > Handwriting analysis

Handwriting analysis (also known as handwriting recognition) is the analysis of handwriting samples, typically for the purpose of matching one sample to another.

When you write, you naturally adopt a relatively unique handwriting that depends on several factors, including:

• How you learned to write: how you learned to form letters and move the writing instrument.
• Your writing habits: how you personally form letters and move the writing instrument, which can be more or less similar to how you learned.
• Your writing level: whether you are learning to write or are an experienced writer.
• The writing instrument: pen, pencil, brush, spray paint can, etc.
• Where you hold the writing instrument: in your right hand, left hand, foot, mouth, prosthesis, etc.
• How you hold the writing instrument: for example, on which of your fingers does a pen rest when you write.
• The writing surface: paper, fabric, concrete, etc.
• Your posture while writing: sitting, standing, etc.
• The writing environment: for example, if you are writing with gloves on or in a moving vehicle.
• Your physical and mental state while writing: fatigue, stress, altered state due to alcohol, drugs or medication, etc.

An adversary can analyze a writing sample to identify its characteristics, including:

• The layout of the text: margins, space between lines, and parallelism of lines. In the case of envelopes: the style, size, and position of the address on the envelope.
• The writing style: for example cursive or block letters.
• The space between characters and between words.
• Connections or separations between characters.
• The design and construction of characters: the shape of characters, whether a character is represented with one or more shapes throughout the sample, the order in which a shape is traced, whether and how a shape is affected by the particular shapes that precede and follow it, and the size of shapes.
• The strokes traced when the writing instrument reaches and leaves the writing surface, including their length, direction, path, and abruptness.
• The pressure exerted by the writing instrument on the writing surface.
• The position of the writing instrument relative to the writing surface.

In some languages that are written horizontally, such as English, an adversary can also identify the following characteristics:

• Whether the baseline^[2] is straight or varies throughout the sample.
• The writing slant: the predominant inclination of characters relative to the baseline.

An adversary can compare the characteristics of a writing sample to the characteristics of another to determine whether or not the samples were written by the same person, and the confidence in that determination. This comparison can be done by humans or by specialized software.

In some countries, the State has databases of handwriting samples that allow comparing a sample to all samples in the database. For example, in the United States, the Federal Bureau of Investigation (FBI) maintains the Bank Robbery Note File (BRNF), which contains samples of handwritten notes used in bank robberies.

See also Huber and Headrick's Handwriting Identification: Facts and Fundamentals ?This is a link to the Surveillance Archive. Use Tor Browser to access it. for a comprehensive overview of handwriting analysis.

Used in tactics: Incrimination

Mitigations

Used in repressive operations