Koh Alaric C W, Oh Suat Ping, Lim Shing Min, Yew Sok Yee, Chen Jean, Chow Vicky Y S
Forensic Chemistry and Physics Laboratory, Health Sciences Authority, Singapore.
Forensic Sci Res. 2019 May 29;5(1):64-73. doi: 10.1080/20961790.2019.1595353. eCollection 2020.
This work highlights the evidential value of examining plastic drinking straws to establish linkages between multiple sources for forensic intelligence, investigative or prosecution purposes. Plastic drinking straws are commonly encountered in drug cases, either as inhalational paraphernalia or as packaging material. However, to the best of our knowledge, systematic studies on the evidential value of straws have not previously been carried out. In this study, over 80 packets of clear and colourless straws-most of which were visually similar-were purchased from various commercial outlets in Singapore. Some physical characteristics (viz., polarizing patterns, thickness, circumference and mass per unit length) and the manufacturing marks of these straws were examined to assess their potentials for discriminating straws from different packets. Comparison of polarizing patterns yielded a discrimination of approximately 69%, while thickness, circumference, and mass per unit length measurements resulted in lower discriminations. Comparison microscopy of manufacturing marks was found to be the most discriminating among all techniques employed herein, with a discrimination of about 95%, even among straws with similar polarizing patterns.
这项工作突出了检查塑料吸管对于为法证情报、调查或起诉目的建立多个来源之间联系的证据价值。塑料吸管在毒品案件中很常见，要么作为吸食用具，要么作为包装材料。然而，据我们所知，此前尚未对吸管的证据价值进行系统研究。在本研究中，从新加坡的各个商业网点购买了80多包透明无色吸管，其中大部分在外观上相似。对这些吸管的一些物理特征（即偏光图案、厚度、周长和单位长度质量）以及制造标记进行了检查，以评估它们区分不同包装吸管的潜力。偏光图案的比较得出的区分率约为69%，而厚度、周长和单位长度质量的测量得出的区分率较低。在所采用的所有技术中，制造标记的比较显微镜检查的区分能力最强，区分率约为95%，即使在偏光图案相似的吸管之间也是如此。
