Detective William Murdoch
莫德克探長是位聰明，善於觀察的偵探，會使用不尋常的辦案技術（以當時來說），例如：驗血和採驗指紋，來調查案件。來自加拿大新斯科舍省，並且是位虔誠的天主教徒。由於受過耶穌會牧師的教導，會說法語。他曾一度以為父親毆打母親，並間接導致母親死亡，但後來證明事實並非如此，不過也因此事件，他被送往孤兒院，由院方撫養長大。
Detective Murdoch is an intelligent, observant detective who uses unusual (for the time) techniques such as blood testing and fingerprinting. Throughout the series it is revealed he comes from Nova Scotia and is a devout Roman Catholic. Due to being educated by Jesuit Priests, Murdoch is fluent in French. In one episode it is revealed that he believes that his father beat his mother and may have indirectly caused her death, although this was proven incorrect. Following that incident, he was taken to live in an orphanage.
Inspector Thomas Brackenreid
巡官Thomas是一位年約四十歲，喜歡看戲和飲酒的已婚男子。他是局內的長官，負責大部分的審問，經常依據個人印象或嫌犯的社會地位而判斷。易怒頑強，喜歡諷刺挖苦別人。習慣於傳統辦案方式，對自己的工作感到驕傲，他認為這是他的責任來保護這座城市。
Inspector Brackenreid is a married man of about forty, fond of the theatre and a good drink. He is the head of the stationhouse and does most of the interrogating, often forming opinions on a suspect because of personal impressions or their social standing. Quick to anger and tenacious, with a sarcastic sense of humour, he is better at traditional "coppering" and is very proud of his job, and what he feels is his duty to protect the city.
Dr. Julia Ogden
Ogden博士是位專業的病理學家和驗屍官。兩姊妹中的姊姊，她年輕時打扮比較中性。母親已經去世，和父親的關係緊張。曾和大學同事裸泳而被抓到，留下犯罪紀錄。大學時曾意外懷孕，而後決定墮胎，這件往事讓莫德克不忍和她分手。她喜歡打網球、閱讀、騎自行車和看戲。
Doctor Ogden is a skilled pathologist and coroner. The first of two sisters, she apparently was a tomboy in her youth. It has been revealed her mother is dead, she has a strained relationship with her father, and she has a criminal record for being caught skinny dipping with some university colleagues.It is revealed she became accidentally pregnant, when in university and terminated it; this causes a horrified Murdoch to end his relationship with her. She enjoys tennis, reading, cycling and attending the theatre.
Constable George Crabtree
莫德克探長的助手Crabtree警官，雖然沒有什麼經驗，但時常在辦案時提供有用的觀點，並且在過程中到各案件現場搜集證據。他雖然有充滿熱忱急切，但還不能完全學會莫德克高超的科學辦案技術。本劇的甘草人物，總是會提供他認為會幫助莫德克解決案件的意見，但其實不會有任何幫助。
Murdoch’s assistant Constable Crabtree is, however inexperienced, often provides useful insights into cases and does much of the forensic legwork collecting evidence. He is eager, but has yet to master Murdoch’s more advanced scientific skills. He isn’t much of a serious character, because he often says random things that he thinks will help Murdoch solve the case, but really do not.