| Summary: | Ballpoint pens are the most common writing implement used to write a document
therefore it is not surprising to see their association with criminal cases such as insurance
fraud, homicide, drug dealing and kidnapping. The ink deposited by a ballpoint pen is the
course of writing a dubious document can reveal useful information about the ballpoint
pen. This study uses pair-wise manual comparison, statistical technique of Pearson
Product Moment Correlation (PPMC) or simply Pearson’s r and chemometric technique
of principle component analysis to determine the ballpoint pen responsible for writing a
simulated threatening note. Eleven (11) blue ballpoint pen inks in which one of them was
used to write a threatening note were subjected to Fourier Transform Infra Red (FTIR)
spectroscopy. The FTIR spectra of the blue ballpoint pen inks were first interrogate using
pair- wise i.e. one to one manual comparison followed by PPMC and PCA. Of three
techniques employed, only PCA through its principle component score plot had
successfully determined the blue ballpoint pen inks responsible for writing the simulated
threatening note . This study revealed that combination of FTIR and PCA can be used to
determine the original source of ink provided that the reference ink is available.
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