《龍圖公案》俗稱《包公案》，是古代典型之代表性偵查小說，全書以宋朝包拯為主角，說明其犯罪偵查過程。為了解古今偵查手段傳承之脈絡，本文以《龍圖公案》之內容以及警政署頒定之警察偵查犯罪手冊中的偵查手法為分析基礎，找出古今相同的偵查策略內容。文章先說明小說情節中之內容，再輔以現代犯罪偵查程序為之說明，俾使讀者了解相關亙古不變之偵查原則。本文討論公案一書中相關偵查作為，包括偵查不公開、諮詢與跟蹤監視、案情研判、以贓追人、公開協尋、地毯式偵查等六項。獲得的結論為：古代的部分偵查技術其作法雖然在今日仍然使用，但隨著科技發展及犯罪型態演變，警方偵查技術必須隨時保持優勢地位，方能有效偵破案件；古今犯罪偵查均同時靠多種偵查技術相互配合方能完成，非僅只單一種策略即可奏效；以及古今犯罪偵查權責與刑事司法體系之規劃有所不同，中國古代犯罪偵查制度，屬於行政與司法體系相結合之情況，地方行政長官同時擁有犯罪偵查與審判之雙重權力，因此書中所見犯罪偵查案例，常常有司法審判之程序在內。

Criminal Cases of Judge Longtu is commonly referred to as Criminal Cases of Master Pao and is a representative investigation fiction in ancient times. The main character is Pao Zheng in the Song Dynasty, and the book depicts his process of crime investigation. In order to recognize ancient and modern investigation measures, this study analyzes the content of Criminal Cases of Judge Longtu and investigation techniques in the manual of police crime investigation issued by the National Police Agency and extracts the same investigation strategies in ancient and modern times. This article first describes the scenarios in the fiction and elaborates upon the modern crime investigation procedure. In order to allow readers to recognize the consistent investigation principles, this study discusses a related investigation on Criminal Cases of Judge Longtu, including principle of secret investigation, consultation and tracking monitoring, judgment of cases, tracking by stolen goods, public searching, and blanket search. The conclusions are as follows. Although some investigation techniques in ancient times are still applied nowadays, with technology development and evolution of crimes, the police's investigation techniques must be superior at all times in order to effectively solve cases. Crime investigation in both ancient and modern times relies on collaboration of various investigation techniques, and is not achieved by mere single strategy. Crime investigation authority and criminal justice system planning in ancient and modern times are different. The Chinese ancient crime investigation system was based on a combination of administration and justice system. Local administrative officials possessed the authority of both crime investigation and judgment. Thus, in the book, justice and judgment tend to be involved in crime investigation cases.