The evaluation of evidence for microspectrophotometry data using functional data analysis

Microspectrophotometry data arise in the study of many forensically applicable situations. The situations here are those of ink and fibres. In a criminal investigation, data associated with a crime scene are compared with data associated with a person of interest. Methods based on the likelihood ratio are often used to evaluate such evidence. A technique known as functional data analysis for determining likelihood ratios using the full spectrum is described. It provides support comparing a proposition of common source with a proposition of different sources for data from the crime scene and from the person of interest. Data are available from ink, woollen and cotton fibres. The effectiveness of the method is assessed using false positive and false negative rates and Tippett plots in the comparison of data from known sources.