Writing Investigation Reports: The Ultimate Guide to Getting It Right

Do you dread the end of an investigation because you hate writing investigative reports? You’re not alone.

However, because it’s an important showcase of the investigation, you can’t skimp on this critical investigation step. Your investigation report reflects on you and your investigation, so make sure it’s as clear, comprehensive, accurate, and polished.

How do you write an investigation report? What are the parts of an investigation report? In this guide, you’ll learn how to make your reports effective and efficient.

What is the Importance of an Investigative Report?

An investigation report can:

1. Spark some sort of action based on the findings it presents
2. Record of the steps of the investigation
3. Provide information for legal actions
4. Provide valuable data to inform control and preventive measures

In short, your report documents what happened during the investigation and suggests what to do next.

In addition, the process of writing an investigation report can help you approach the investigation in a new way. You might think of more questions to ask the parties involved or understand an aspect of the incident that was unclear.

Investigation Report “Musts”

Before you begin, it’s important to understand the three critical tasks of a workplace investigative report.

1. It must be organized in a such way that anybody internally or externally can understand it without having to reference other materials. That means it should have little to no jargon or specialized language and be a stand-alone summary of your investigation from start to finish.
2. It must document the investigative findings objectively and accurately and provide decision makers with enough information to determine whether they should take further action. With just one read-through, stakeholders should be able to understand what happened and how to handle it.
3. It must indicate whether the allegations were substantiated, unsubstantiated, or whether there’s something missing that is needed to reach a conclusion. Use the evidence you’ve gathered to back up your analysis.

You might be wondering, “What are the contents of an investigation report?” Now that you know what your report should accomplish, we’ll move on to the sections it should include.

Executive Summary

The executive summary should be a concise overview of the investigation from beginning to end. It should not contain any information that is not already in the investigation report.

This may be the most important component of the investigation report because many readers won’t need to go beyond this section. High-level stakeholders get an overall picture of the allegations, investigation, and outcome without having to pore over the details.

To make this section easy to read, write in an active voice. For example: “I interviewed Carrie Smith,” not “Carrie Smith was interviewed.”

Example: On February 23^rd, 2023, the Human Resources Manager received a written complaint of sexual harassment submitted by Carrie Smith, the stockroom manager. Smith claimed that on February 22^nd, 2023, her supervisor, Mark Robinson, pushed her against the wall in the boardroom and groped her breasts. Smith also alleged that Robinson on another occasion told her she was “too pretty” to be working in the stockroom and that he could arrange for a promotion for her. 

On February 24th, the Human Resources Manager assigned the case to me.

On February 25th, I interviewed Carrie Smith and two witnesses to the alleged February 22^nd incident, John Jones and Pamela Miller. Jones and Miller did not corroborate the groping allegation but said they saw Smith running out of the boardroom in tears. Miller also reported hearing Robinson tell another employee, Sara Brown, that she had “a great rack”. 

On February 26^th, I interviewed Mark Robinson. He denied the groping incident and said he was “just joking around” with her in the boardroom but did not actually touch her and that Smith was too sensitive. He admitted to telling Smith she was too pretty to work in the stockroom, but contends that it was meant as a compliment.

Based on the interviews with the complainant and the alleged offender, I find that the complainant’s allegation of sexual harassment is substantiated.

It is my recommendation that the company provide the respondent with a written account of the findings of the investigation and a reminder of the company’s expectations for employee behavior. I also recommend that the respondent receive sexual harassment training and be advised that repeated harassing behavior may result in further discipline up to and including termination.

Preliminary Case Information

This section outlines the preliminary case information in a concise format, with only the most important details. It can go either before or after the executive summary.

Record:

• Your name and investigator identification number, if you have one
• Case number
• Date the case was assigned to you
• The date the report was reviewed
• How the report was received (e.g. hotline, email to HR manager, verbal report to supervisor)
• Name of the reporter/complainant

If the reporter is an employee, record their:

• Email address
• Work telephone number
• Employment level/position
• Job code
• Hire date
• Location
• Employee identification number
• Department identification number

If the source is not an employee, only record their:

• Email address
• Personal telephone number

In either case, note the date that the report was submitted, as well as the date(s) of the alleged incident(s).

Incident Summary

The purpose of this section is to answer the who, what, where, and when about the incident.

1. What type of case is it? For example, is the case alleging harassment, discrimination, fraud, or other workplace misconduct?
2. Specify the case type further. For example, is it sexual harassment, gender discrimination, accounts payable fraud, etc.
3. Who is the alleged victim? For example, is it the reporter, another employee, a customer, or the whole company?
4. If the alleged victim is an employee, identify the person’s supervisor.
5. Were any other people involved besides the subject and the alleged victim?
6. Where did the incident(s) take place?
7. When did the incident(s) occur?
8. Capture details of the allegation. Example: Stacey Smith alleges that John Jones, an accounts payables clerk, has been funneling payments to a dummy supplier that he has set up in the company’s procurement system. Stacey says that she noticed a discrepancy when one of the suppliers she deals with questioned a payment and she had to ask an accounts payable clerk, Tom Tierney, to pull the file for her. When Tom accidentally brought Stacey the wrong file, she saw that monthly payments were being made to a supplier she had never heard of, and that the address of the supplier was John Jones’s address. Stacey knows John’s address because her sister is John’s next-door neighbor.

Describe the allegation or complaint in simple, clear language. Avoid using jargon, acronyms, or technical terms that the average reader outside the company may not understand.

Allegation Subject

In this section, note details about the alleged bad actor. Some of this information might be included in the initial report/complaint, but others you might have to dig for, especially if the subject isn’t an employee of the organization.

For every subject, include their:

• Name
• Email (work contact if they’re an employee, personal if not)
• Telephone number (see above)

If the subject of the allegation is an employee, also include their:

• Employment status (e.g. full-time, part-time, intern, contractor, etc.)
• Job code
• Hire date
• Business location
• Employee identification number
• Department identification number

Investigation Details & Notes

Begin outlining the investigation details by defining the scope. It’s important to keep the scope of the investigation focused narrowly on the allegation and avoid drawing separate but related investigations into the report.

Example: The investigation will focus on the anonymous tip received through the whistleblower hotline. The objective of the investigation is to determine whether the allegation reported via the hotline is true or false.

Next, record a description of each action taken during the investigation. This becomes a diary of your investigation, showing everything that was done during the investigation, who did it, and when.

For each action, outline:

• Type of action (e.g. initial review, meeting, contacting parties, conducting an interview, following up)
• Person responsible for the action
• Date when the action was completed
• Brief description of the action (i.e. who you met with, where, and for how long)

Be thorough and detailed, because this section of your report can be an invaluable resource if you are ever challenged on any details of your investigation.

Investigation Interviews

Write a summary of each interview. These should be brief outlines listed separately for each interview.

Include the following information:

• Who conducted the interview
• Who was interviewed
• Where the interview took place
• Date of the interview

Include a list of people who refused to be interviewed or could not be interviewed and why.

Write a Report for Each Interview

This is an expanded version of the summaries documented above. Even though some of the information is repeated, be sure to include it so that you can use the summaries and reports separately as standalone documentation of the interviews conducted.

For each interview, document:

• Who conducted the interview
• Who was interviewed
• Location of the interview
• Date of the interview
• Summary of the substance of the interview, based on your interview notes or recording.

Example: I asked Jane Jameson to describe the events of July 13^th, 2016. She said: “After work, Peter approached me as I was leaving the building and asked me if I would like to work on his team. When I said that I was happy working with my current team, he told me that my team had too many women on it and that ‘all those hormones are causing problems’ so I should think about moving to a ‘sane’ team.”

I asked her how she reacted to that. She said: I told him that I found that offensive and he said that I needed to stop being so sensitive. I just walked away.”

I asked Jane to describe the events of the next day. She said: “The next day he came to my desk and asked me if I had given any thought to moving to his team. I repeated that I was happy where I was. At that point he started massaging my shoulders and said that moving to his team would have its ‘perks’. I asked him to stop twice and he wouldn’t. Sally walked over and told him to get lost and ‘leave Jane alone’ and he left.”

I thanked Jane for her cooperation and concluded the interview.

Assess Credibility

Aside from collecting the evidence, it is also an investigator’s job to analyze the evidence and reach a conclusion. Include a credibility assessment for each interview subject in the interview report. Describe your reasons for determining that the interviewee is or isn’t a credible source of information.

This involves assessing the credibility of the witness. The EEOC has published guidelines that recommend examining the following factors:

• Plausibility – Is the testimony believable and does it make sense?
• Demeanor – Did the person seem to be telling the truth?
• Motive to falsify – Does the person have a reason to lie?
• Corroboration – Is there testimony or evidence that corroborates the witness’s account?
• Past record – Does the subject have a history of similar behavior?

Example: I consider Jane to be a credible interviewee based on the corroboration of her story with Sally and also because she has nothing to gain by reporting these incidents. She has no prior relationship with Peter and seemed genuinely upset by his behavior.

Evidence

In this section, describe all the evidence obtained. This could include:

• Video or audio footage
• Email or messaging (e.g. Slack, Teams, etc.) records
• Employee security access records
• Computer or other device login records
• Documents or papers
• Physical objects (e.g. photos, posters, broken objects, etc.)

Number each piece of evidence for easy reference in your chain of evidence document.

As you gather and analyze evidence, it’s critically important to include and fully consider everything you find. Ignoring evidence that doesn’t support your conclusion will undermine your investigation and your credibility as an investigator. If you aren’t weighing some pieces as heavily as others, make sure you have a good explanation as to why.

Conclusion & Recommendations

In the final section of your report, detail your findings and conclusion. In other words, answer the questions that your investigation set out to answer.

This is where your analysis comes into play. However, be sure to only address the issue(s) being examined only, and don’t include any information that is not supported by fact. Otherwise, you could be accused of bias or speculation if the subject challenges your findings.

Example: My findings indicate that, based on the evidence, Bill’s allegation that Jim blocked him from the promotion is true. Jim’s behavior towards Bill is consistent with the definition of racial discrimination. The company’s code of conduct forbids discrimination; therefore, Jim’s behavior constitutes employee misconduct.

It’s important for your conclusion to be defensible, based on the evidence you have presented in your investigation report. Reference reliable evidence that is relevant to the case. Finally, explain that you’ve considered all the evidence, not just pieces that support your conclusion.

In some cases, you might have been asked to provide recommendations, too. Depending on your conclusion, you may recommend that the company:

• Does nothing
• Provides counselling or training
• Disciplines the employee(s)
• Transfers the employee(s)
• Terminates or demotes the employee(s)

Example: It is my recommendation that the company provide the respondent (Jim) with a written account of the findings of the investigation and a reminder of the company’s expectations for employee behavior. I also recommend that the respondent (Jim) receive anti-discrimination training and be advised that repeated discriminatory behavior may result in further discipline up to and including termination.

Final Edits

Grammatical errors or missed words can take even the best investigation report from professional to sloppy. That’s why checking your work before submitting the report is perhaps the most important step of them all.

Keep in mind that your investigative report may be seen by your supervisors, directors, and even C-level executives in your company, as well as attorneys and judges if the case goes to court.

If spelling, grammar, and punctuation aren’t your strong suit, enlist the services of a writer-friend or colleague to proofread your report. Or, if you’re a lone wolf kind of worker, upgrade your skills with a writing course or a read-through of books like The Elements of Style by Strunk and White. At the very least, remember to run a spell check before you pass on any document to others.

Finally, do a quick scan to make sure you’ve included all the necessary sections and that case details are consistent.