External vs. Internal Workplace Investigations: Which Is Right for Your Organisation?

You’ve received a workplace complaint and you know it needs to be investigated. The next question is: who’s going to do it? Do you hand it to your HR team to manage internally, or do you bring in an external workplace investigator?

It’s not always an obvious call. Both options have their place. But in my experience, organisations get this decision wrong more often than they get it right – usually because they default to the cheaper or more convenient option without thinking through the consequences. And by the time they realise the investigation has a credibility problem, it’s too late to fix it.

Let’s break down when each approach works, when it doesn’t, and how to make the right call for your situation.

Internal Workplace Investigations: When They Work

An internal workplace investigation is conducted by someone within the organisation, usually a senior HR professional, an in-house lawyer, or sometimes a manager with appropriate training.

Internal investigations can work well when the complaint is relatively straightforward – a single allegation, limited witnesses, no involvement of senior leadership, and no pre-existing tensions that could compromise the process. If your HR team is trained in workplace investigations and has the time and capacity to manage the process properly, handling a low-level complaint internally can be efficient and cost-effective.

Advantages of Internal Investigations

Cost. The most obvious one. You’re using existing staff, so there’s no external fee. For straightforward matters, this can make good financial sense.

Organisational knowledge. An internal investigator already understands the culture, the policies, the reporting lines, and the context. They don’t need a briefing on how the organisation works.

Speed. In theory, an internal investigator can get started immediately without the procurement process of engaging an external provider.

The Problems with Internal Investigations

Here’s where it gets tricky. The advantages of internal investigations are also their weaknesses.

Perceived bias. This is the big one. No matter how fair and competent your HR team is, an internal investigator is employed by the same organisation as the complainant and the respondent. They report to the same leadership. They have ongoing working relationships with the people involved. For the person making the complaint, it’s entirely reasonable to wonder: can this person really be impartial when their boss is the one being complained about?

Capacity and competing priorities. Internal investigators rarely have the luxury of dropping everything to focus on an investigation. They’re still doing their day job, still answering emails, still getting pulled into meetings. Investigations get squeezed in between everything else, and timelines blow out. I’ve seen internal investigations take four months for matters that an external investigator would have wrapped up in four weeks.

The aftermath problem. Here’s something nobody talks about: the internal investigator still has to work with these people once the investigation is done. They have to sit in meetings with the person they didn’t substantiate allegations against. They have to manage the HR file of the person who was disciplined based on their findings. That’s an incredibly uncomfortable position, and it can – consciously or unconsciously – influence how they approach the investigation in the first place.

Training gaps. Being a good HR professional doesn’t automatically make someone a good investigator. Workplace investigations require specific skills in evidence gathering, interviewing, procedural fairness, and report writing. If your HR team hasn’t been formally trained in these areas, the investigation may not withstand scrutiny.

External Workplace Investigations: When to Bring Someone In

An external workplace investigation is conducted by an independent professional engaged specifically for the matter. This is typically a specialist workplace investigator, a lawyer with investigation experience, or someone with a background in both.

Advantages of External Investigations

Independence and credibility. An external investigator has no stake in the outcome and no ongoing relationship with the parties. This is the single most important factor in whether the people involved trust the process. And trust in the process is everything. If the complainant doesn’t believe the investigation was fair, you’ll end up dealing with a second complaint about the investigation itself.

Dedicated focus. An external investigator is engaged to do one thing: investigate this matter. They’re not juggling it alongside their regular workload. This typically means faster turnaround and a more thorough process.

Specialist expertise. Experienced external investigators do this all day, every day. They know how to manage complex interviews, navigate procedural fairness requirements, and write reports that stand up to legal challenge. They’ve seen the patterns and they know the pitfalls.

Related reading: Who Should Conduct a Workplace Investigation?

Risk management. If the matter ends up at the Fair Work Commission, in a workers’ compensation claim, or before a regulator, having an independent, external investigation significantly strengthens your position. It demonstrates that the organisation took the complaint seriously and managed the process with integrity.

The Downsides of External Investigations

Cost. Let’s be honest about it. External investigators charge fees, and for complex matters, those fees add up. But I’d argue the cost of a proper external investigation is almost always less than the cost of getting it wrong internally – in terms of legal exposure, staff turnover, workers’ compensation claims, and reputational damage.

Ramp-up time. An external investigator needs to be briefed on the organisation, its policies, and the context of the complaint. This takes time at the outset, though a good investigator will manage this efficiently and it rarely adds more than a day or two to the overall timeline.

How to Decide: A Practical Framework

Forget about cost for a moment. The question you should be asking is: will the people involved trust this process?

If the answer is yes – if the complaint is straightforward, the HR team is trained and credible, and there’s no conflict of interest or perception of bias – an internal investigation may be perfectly appropriate.

If there’s any doubt, go external. Specifically, consider an external workplace investigation when:

The complaint involves senior leadership or management. When the person being complained about has power within the organisation, an internal investigation will always struggle for credibility – even if it’s conducted perfectly.

There are multiple or complex allegations. Matters involving several allegations, multiple parties, or allegations spanning a long period need specialist skills and dedicated time that most internal teams can’t provide.

There’s potential legal exposure. If the matter could result in a Fair Work claim, an anti-discrimination complaint, a workers’ compensation claim, or regulatory action, you need an investigation that will withstand external scrutiny.

Trust in the organisation is already low. If employees are cynical about the organisation’s willingness to address complaints fairly, an internal investigation will confirm their worst assumptions. An external investigator sends a clear message that the organisation is taking the matter seriously.

The complaint involves systemic or cultural issues. If the complaint suggests problems that go beyond one individual – a culture of bullying, widespread harassment, or systemic unfairness – the investigation needs to come from outside the system it’s examining.

The HR team has a conflict of interest. If HR is friends with the respondent, reports to the person being complained about, or has been part of the problem, they cannot investigate it. Full stop.

The Psychosocial Safety Dimension

Under current WHS laws, employers have a positive duty to manage psychosocial risks in the workplace. The way you conduct a workplace investigation has a direct impact on the psychological safety of everyone involved.

An investigation that’s perceived as biased, that takes too long, or that’s conducted by someone too close to the situation doesn’t just produce unreliable findings – it actively harms the people involved. The complainant feels dismissed. The respondent feels targeted. The rest of the team loses faith in the organisation’s ability to keep them safe.

Choosing between an internal and external investigation isn’t just a procurement decision. It’s a workplace safety decision. And it should be treated with that level of seriousness.

The Bottom Line

There’s no one-size-fits-all answer to the external vs. internal workplace investigation question. But there is a simple test: if you have any doubt about whether an internal investigation will be trusted, believed, and respected by the people involved, bring in someone from outside.

The cost of an external investigator is predictable and contained. The cost of an investigation that nobody trusts – in legal fees, staff turnover, compensation claims, and cultural damage – is not.

Need an independent, external workplace investigation? Segal Conflict Solutions provides external workplace investigations in Sydney and across Australia, delivering thorough, impartial findings your organisation can rely on. Get in touch for a confidential discussion.