Yes, several digital telltale signs can indicate a signature was made by an autopen, even when viewed digitally. The primary methods for detection rely on forensic analysis of the physical characteristics that reveal a mechanical origin, which can be observed with magnification or digital analysis tools.
Key digital forensic signs to look for include:
Uniform Pressure and Line Width: A human signature naturally has variations in pen pressure, leading to differences in ink thickness and paper indentation. Autopens tend to apply constant, even pressure, resulting in lines of exactly the same width throughout the signature.
Abrupt Starts and Stops: Humans lift the pen smoothly from the page, creating a tapering effect. Autopens start from a static position and stop abruptly at the end of each stroke, which can cause a small blob or pooling of ink at these points.
Identical Reproduction: The most definitive sign is that an autopen produces an exact replica every time. By comparing a signature to other known samples from the same person, a forensic expert can determine if they are identical overlays, which indicates mechanical reproduction.
Lack of Flow/Shakiness: Autopen signatures may appear to have a "drawn" or slightly shaky look, especially in long, fast strokes, due to the mechanical movement, which is different from the natural flow of a human hand.
No Paper Indentation Variability: While digital images might not immediately show physical indentation, high-resolution scans can reveal the uniform depth of the groove the pen made in the paper, contrasting with the irregular depth of a genuine signature.
Ink Crossing Points: Under high magnification, genuine signatures will show a darker spot where one trace of ink crosses another, due to the double layer of ink. While some modern machines can replicate this to an extent, the trace is often too regular.
Ultimately, forensic handwriting experts use magnification, UV light, and comparison libraries of known autopen patterns to make a definitive determination. Modern high-end machines can make detection very difficult, so consulting a professional is the surest method for authentication.