Matrimonial & Infidelity Investigations

Updated 31 July 2026 by K3K Investigations

When you no longer believe what you are being told, certainty is the only thing that helps. K3K conducts discreet, lawful matrimonial investigations across the UK — and delivers a clear answer either way, with evidence rather than suspicion.

This is the most personal work we do, and it arrives with people at their worst moment. Two things are worth saying immediately. First: a professional investigation clears the other person surprisingly often, and that is a real result, not a wasted fee. Second: you never have to explain yourself to us. Whatever the situation, we have seen it, and none of it is judged.

Call 020 3343 7007 — 24 hours, free, confidential. If you share a home with the person, we will agree safe contact times and a discreet method of communication from the very first call.

What a matrimonial investigation establishes

• Where someone actually is during the hours they have accounted for differently — the working late, the gym, the trip away.
• Who they are with, documented with timestamped photographic and video evidence gathered in public places.
• Patterns rather than moments. A single evening proves little; a documented pattern across the right days is what converts suspicion into certainty.
• A second household, a second life, or money leaving the marriage — often the part that matters most where finances are shared.
• Verification of an identity where you have been told about someone but shown nothing.

How the operation works

1. Free confidential consultation. You tell us what you have observed and what you need to know. We are direct about whether surveillance can realistically answer it — sometimes the honest advice is that it cannot, or should not, and we give that advice free.
2. Planning around the truth, not the hope. We choose the days and hours where the answer actually lives — usually the specific occasions you already suspect — so you pay for the smallest operation that can settle it.
3. Deployment. Experienced surveillance operatives, covert vehicles and equipment, observing lawfully in public. Nothing that would embarrass you or alert the subject.
4. Reporting. A written, timestamped report with clear imagery, delivered exactly how and when you choose — including arrangements that keep it invisible at home.

Our covert surveillance page explains the fieldwork discipline in more detail, and Three Thursdays in South London is an anonymised account of how a real matrimonial operation unfolded.

Evidence that stands up if it needs to

Most clients want peace of mind rather than a court case. But if proceedings follow — divorce, finances, or arrangements for children — evidence gathered lawfully by a professional agency, timestamped and chain-of-custody logged, is usable and credible. Evidence obtained by hacking a phone, installing spyware or unlawfully tracking a vehicle is not: it is inadmissible at best, criminal at worst, and it hands the other side a weapon. That is the single most important reason to use an agency rather than doing it yourself.

What we will not do

We do not access phones, email or social accounts; we do not obtain bank or phone records by deception; we do not track vehicles without a lawful basis established first — see our GPS tracker law guide. And we decline cases where the pattern suggests control or intimidation rather than a genuine question. If you are frightened of the person you are asking about, tell us on the first call — the right help may not be an investigator, and we will point you to it.

Frequently asked questions

Is it legal to hire a private investigator to follow my partner?

Yes. Surveillance conducted in public places, proportionately and for a legitimate purpose, is lawful in the UK. The methods are what the law restricts, not the instruction. Our guide is it legal to hire a private investigator covers exactly where the lines sit.

Will my partner find out I hired an investigator?

Not from us. Operatives are trained to remain unnoticed, cases are handled need-to-know internally, and we adapt every contact to your circumstances — including agreed call windows, alternative email, and holding reports until you are somewhere you can read them safely.

How much does a matrimonial investigation cost?

Most matrimonial cases are one to three days of surveillance. Realistic UK day rates are £500–£1,200 per operative including vehicle, equipment and reporting, and we agree a fixed price in writing before we deploy. Full context in our cost guide.

What if the investigation finds nothing?

Then you have your answer, and it is a good one. About a third of our matrimonial cases end with the partner cleared — the "late meetings" really were meetings. A professional negative is evidence too, and most clients describe the relief as worth the fee on its own.

Can I just check their phone instead?

Please do not. Accessing someone's device or accounts without consent is an offence under the Computer Misuse Act, it makes anything you find unusable, and in practice it produces fragments that inflame the suspicion without resolving it — a name, a deleted thread, and no context. Our guide on the signs of a cheating partner explains what to do instead.

Stop guessing. Know. A free, confidential conversation with a senior investigator — 020 3343 7007, 24 hours. If you share a home, we will agree safe contact arrangements from the first call.

Related reading: Signs of a cheating partner · Covert surveillance · Three Thursdays in South London