「13. 本席考慮了雙方的陳詞，亦都考慮了相關的案例以及書籍，當中包括Phipson on Evidence 19th edition 第[15-34]段，R v Castleton [1909] 3 Cr App R 74，HKSAR v Chiu Wai Keung (FAMC [59/2012]，CACC 441/2011) ，香港特別行政區 訴 孫俊文 (CACC 441/2004) ，HKSAR v Wong Wai Leung (CACC 494/2003) ，HKSAR v Syed Rashid Aslam (CACC 204/2017) 。
14. 終審法院在Chiu Wai Keung 的判詞第9段指： “depending on the circumstances of each case, the presence of an accused’s fingerprint at the scene of crime may be sufficient to form the basis of a conviction.”
15. 上訴法庭在該案件的判詞指出包括以下幾點 (見[2013] 1 HKC 45 Headnote (holdings)):
“(1) While the circumstances in which a fingerprint may be found and a cogency of such evidence may differ from case to case, it had long been the law that a court may rely on a fingerprint as the sole evidence of identification.
(2) If a defendant’s fingerprint is found inside locked premises, where he should not normally have been and, everyone, other than a very restricted section of people, was prohibited access, and when there was no obvious explanation as to why the fingerprint should have been there, a judge (or a jury) was, depending on the circumstances, entitled to infer that he was a party to the burglary. It was not a matter of requiring the defendant to give an innocent explanation for the presence of his fingerprint; it was to permit the drawing of an appropriate inference from the fact that it should not otherwise have been there…
(5) In the absence of any evidence or explanation by the applicant, the trial judge was right that it was not for him without any evidential basis to speculate how a fingerprint might have been innocently left on the inside of a locked door by someone with no apparent connection with the building. He was entitled to draw the appropriate inference that the applicant was present at the premises.”
16. 在本案，信紙P3以及毒品P4是在一個封了口的信封P2內，懲教署人員拆開信封之前是完整無缺，未被啟開的。信紙P3上有被告人的兩個手指模，他同意這一點。
17. 被告人的兩個手指模是在一個密封的信封內的信紙上，並且在信紙底部以及信紙面均有他的指模 – 其中一個是右手手指印上的指模，另外一個是左手手指印上的指模 – 這顯示被告人是有拿起過以及處理過P3紙張，並且觸摸過多次。P2-P4並沒有任何其他人的指模。
18. 本席認為，唯一的合理推論是被告人是寫信的人，而他是寫上P3當中的文字時，將手指模印了上信紙P3。
19. 另外，信封寫上壁屋懲教所的地址以及洪先生的犯人號碼，而且信上的內容提及『你要的我帶來了』，信中提及『帶來了』的東西一定是和P3一起密封在信封P2的毒品P4。唯一的合理推論是寫信的人 (即是被告人) 刻意將毒品P4連同信件P3放入信封P2內，並且將信和毒品密封在信封，一同寄給在壁屋懲教所的犯人409368 (即是洪先生) 。
……
21. …終審法院在 Chiu Wai Keung (FAMC [59/2012]) 第7段指出： “since it was not known what the defence case was, it was not incumbent upon the prosecution to exclude all the possibilities why the defendant’s fingerprint found its way to a place where entry and presence was restricted.”
……
25. 而本席認為，其實在本案相關的手指模印在封著了的信內，比爆竊案有手指模印在竊案單位證據更加強 – 如果法庭真的需要作出猜測，一名被告人的手指模在爆竊單位出現的可能無辜原因 (innocent reasons) (例如，被告人其實是有權限進入被爆竊處所的維修工人，或者被告人跟隨有關權限的工作人員進入，並且留下指模：見 [2013] 1 HKC 45第19及41段) ，必定多過被告人的手指模會印在P3信紙上的無辜原因：除了在寫信的時候重複觸摸一張信紙導致留低了手指模，被告人還有什麼其他原因會觸摸這張信紙多次導致有幾個手指模印在信紙上？但是無論如何，正如上訴庭指出： “in the absence of any evidence and explanation by the defendant, it is not for the Court without any evidential basis to speculate how a fingerprint might have been innocently left” 。
26. 本席亦留意到，並不是所有關於指模證據的案例都牽涉爆竊罪。舉例說，HKSAR v Syed Rashid Aslam (CACC 204/2017) 中，被告人面對的是『以欺騙手段取得財產』罪，控方指稱被告人利用受害人的信用卡買了一隻手錶，而案中唯一指證被告人的證據是在信用卡收據的手指模 (“the applicant’s fingerprint found on the receipt was the only evidence which linked the applicant to the credit card” （見第15段）) 。上訴庭在拒絕給予上訴許可時指出：
“30. A person may be identified by fingerprint evidence alone: R v Castleton. Further, as the appellate committee of the Court of Final Appeal held in HKSAR v Chiu Wai Keung, at para 9:
‘…depending on the circumstances of each case, the presence of an accused’s fingerprint at the scene of crime may be sufficient to form the basis of a conviction’.
31. In the present case, it was not disputed that the applicant’s left thumb print was found on the original credit card receipt issued in respect of the watch in question. Indeed, the applicant gave an elaborate explanation as to why his fingerprint may have appeared on the receipt ostensibly signed by the card holder. However, the judge rejected that explanation.
32. I can see no reasonable ground of appeal for saying that the judge was wrong to reject the applicant’s explanation. As the judge found, it was an incredible account, which not only defied common sense and normal commercial practice, but it was refuted by PW2, who described it as ‘impossible’. Once that account, and that of DW2, were rejected, the only reasonable inference to draw, as the judge found, was that the applicant had placed his thumb print on the receipt at the time he used the stolen credit card to obtain the watch in question.”
…
30. 值得一提的是，終審法院在Chiu Wai Keung 第9段指出：
“…In the present case, it cannot be said that in the circumstances of the case, the presence of the applicant’s fingerprint inside the switch room where entry and presence was restricted and where a burglary had taken place was not sufficient for drawing the irresistible inference that he must have been involved in the crime. There was simply no other basis for drawing a different inference. In this connection, it is apt to refer to the following comment made by the Australian High Court in Weissensteiner v The Queen (1993) 178 CLR 217, 227, 229) which was cited with approval by Lord Hoffmann NPJ in Li Defan and antoher v HKSAR (2002) 5 HKCFAR 320,333,
‘There is a distinction, no doubt a fine one, between drawing an inference of guilt merely from silence and drawing an inference otherwise available more safely simply because the accused has not supported any hypothesis which is consistent with innocence from facts which the jury perceives to be within his or her knowledge.’ ”
31 本席已經考慮了所有相關情況，包括信件的內容、被告人左手及右手指模都印了在信紙上，除了被告人的手指模，沒有其他指模，以及相關的信P3和毒品P4是密封的信封P2內，本席認為唯一不可抗拒的推論是被告人寫了這一封信，並且將信連同毒品放入相關的信封內並且封了口，寫上地址，最後寄到壁屋懲教所。」