How to make detective: the selection process, the interview and the first 90 days

Rank or assignment? Find out first

In many departments "detective" is a specialized assignment chosen by interview and supervisor recommendation. In others (and in many large civil service cities) it is a tested rank with a written exam and a list. Read the posting, the civil service rules and your labor contract before you prepare, because the two paths reward different things.

If it is an assignment, the panel is mostly judging risk: will this officer close cases, write clean affidavits and hold up on the stand? If it is a tested rank, your list position matters most and your file is a tie-breaker.

What panels look for

• Report quality. Pull your last 20 reports and read them like a defense attorney. Clear timelines, elements of the offense and articulated probable cause beat volume.
• Case follow-through: arrests that held, warrants you wrote, search warrants that survived suppression motions.
• Interview and interrogation training, evidence handling and any digital-evidence work.
• Court experience, and whether prosecutors would call you reliable.
• Self-starting: cases you developed from patrol, not just ones you were handed.

Build the file 6–12 months out

• Ask to shadow or assist investigators on a call-out. Volunteer for follow-ups on your own cases.
• Take one or two targeted courses (interview and interrogation, search warrant writing, digital evidence, sex crimes or financial crimes, depending on the unit). Log them in your ServiceJacket profile so the dates and hours are ready for the memo.
• Keep a running list of cases with case numbers, what you did and the outcome. Panels remember specifics.

The interview

• Expect a mix of background questions ("Walk us through a case you are proud of"), scenario questions ("You get a burglary series with no witnesses. What are your first 48 hours?") and ethics questions.
• Answer scenarios in a steady order: scene safety and victim care, preserve evidence, canvass and video, records and databases, interviews, partners (crime lab, prosecutors, other agencies), documentation, and follow-up.
• Use a story structure for experience questions: the situation, what you did, the result, and what you would do differently.

Your first 90 days

• Learn the case management system and the unit's unwritten rules on call-outs and overtime.
• Build prosecutor relationships early. Ask a senior ADA what makes a filing package easy to accept.
• Track every case and every training hour from day one. Investigators who document well get the next assignment.

Reading to gather

• Your agency's investigations and evidence policies
• Your state's search warrant and interview law updates
• Recent case law summaries from your prosecutor's office

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