The Detective's Philosophy
It is a situational irony that the detective uses lies to get to the truth in any major case. The detective says that he values truth and to get to it he must use lies. The reader would have expected that he stay true to one cause which is truth.
The Murder Squad's Reaction to Cassie's Appointment
When Cassie was appointed to the murder squad, she was among the first women to ever get the job. The other members of the unit were skeptical that she could not perform her job well because she was a woman. It is ironical for the members of the squad to judge her ability to perform at her job by her gender rather than her past experience in a drug squad.
The Detectives' Dressing
The narrator tells us that the detectives were always smartly and sharply dressed in the most expensive suits. It is a situational irony that they dressed like this yet the could hardly afford the clothes that they were wearing. They bought them on sales days because the prices were down. They pressured themselves into looking expensive in order to impress and intimidate people.
The Narrator's attraction to women
It is a situational irony that Detective Ryan is attracted to women who annoy him. This is ironical because we would expect him to be attracted to women he liked or who pleased him. Detective Ryan was attracted to Cassie because she annoyed him by dressing casually to work.
Tearing down of an archeological site
In the town of Knockaree, there is an archeological site that has historical sites of The Stone Age, the age of the Vikings and The Neolithic Period. It is therefore ironical that the Irish government wanted to tear the place down to build a motorway rather than preserve their history.