The forensic scenario, on which the round robin study was based, simulated a suspected intentional manipulation
of a real estate rental agreement consisting of a total of three pages. The aims of this study were to (i) establish
the amount and reliability of information extractable from a single type of evidence and to (ii) provide suggestions on the most suitable combination of compatible techniques for a multi-modal imaging approach to
forgery detection. To address these aims, seventeen laboratories from sixteen countries were invited to answer
the following tasks questions: (i) which printing technique was used? (ii) were the three pages printed with the
same printer? (iii) were the three pages made from the same paper? (iv) were the three pages originally stapled?
(v) were the headings and signatures written with the same ink? and (vi) were headings and signatures of the
same age on all pages? The methods used were classified into the following categories: Optical spectroscopy,
including multispectral imaging, smartphone mapping, UV-luminescence and LIBS; Infrared spectroscopy,
including Raman and FTIR (micro-)spectroscopy; X-ray spectroscopy, including SEM-EDX, PIXE and XPS; Mass
spectrometry, including ICPMS, SIMS, MALDI and LDIMS; Electrostatic imaging, as well as non-imaging
methods, such as non-multimodal visual inspection, (micro-)spectroscopy, physical testing and thin layer
chromatography. The performance of the techniques was evaluated as the proportion of discriminated sample
pairs to all possible sample pairs. For the undiscriminated sample pairs, a distinction was made between undecidability and false positive claims. It was found that none of the methods used were able to solve all tasks
completely and/or correctly and that certain methods were a priori judged unsuitable by the laboratories for
some tasks. Correct results were generally achieved for the discrimination of printer toners, whereas incorrect
results in the discrimination of inks. For the discrimination of paper, solid state analytical methods proved to be
superior to mass spectrometric methods. None of the participating laboratories deemed addressing ink age
feasible. It was concluded that correct forensic statements can only be achieved by the complementary application of different methods and that the classical approach of round robin studies to send standardised subsamples to the participants is not feasible for a true multimodal approach if the techniques are not available at one location.