A good police report accurately describes the elements of a crime. It requires the officer to write clearly, concisely and effectively; relay information accurately; and describe the events in a chronological order. There are writing techniques, such as using short sentences and active construction, which aid the readability of a report and can support the officer during cross-examination.
Keep the report accurate. What you write in your reports can become fodder for defence attorneys, investigators, witnesses, experts and others as they read it critically, looking for holes and inaccuracies. Therefore, be as accurate as possible. For example, if a witness says he watched an event for 15 minutes, review that carefully with him as he may have inadvertently exaggerated the time frame. Also, don't add your slant to what a witness says. In our same example, if the witness says an event lasted 15 minutes, don't add the phrase "or less" unless the witness actually said this.
Write events in a chronological order. Just as a story has a beginning, middle and end, the police report needs to describe the events in a chronological, beginning to end, flow. This lets the reader more easily grasp what occurred and understand the elements of the crime without getting confused and needing to go back and fill in the gaps.
Refrain from editorialising. Offering extraneous details gives defence attorneys room to impugn the investigation. Keep it direct, concise and to the point. Also, keep your opinions to yourself. If opinions find their way into your police report, and if the case goes to a hearing or trial, those extraneous details may be used against you on cross-examination.
Encourage witnesses to be factual. Witnesses and victims at the scene of a crime might be overly emotional, frightened or even noncommunicative. Encourage them to stick to the facts and provide complete descriptions. Ask them to repeat information, because if the repeated information is consistent, it's more likely to be accurate.
Keep your sentences short. Short sentences encourage precision. If the case goes to a hearing or trial, your statements in a police report are the script for your cross-examination answers. If you write long, meandering, complicated sentences, a trial attorney may use those words to try to impeach you.
Keep the report active. It's critical in a police report to specify who did what, and active construction helps you do this. Passive construction, on the other hand, blurs who did the action. For example, "Subject A received the money, then hid it in a bag" is active because it clearly identifies the subject and her actions. On the other hand, "The money was received and hidden in a bag" is passive and does not identify who received the money and hid it.
Purchase a book on effective writing. A book on writing can help you better apply structure, grammar and punctuation to your narrative, which in turn helps you write more concise, clear and factual reports. One classic reference book on writing is "The Elements of Style" by William Strunk, Jr.