Signs you may be under surveillance

What are the usual warning signs?

Each sign has ordinary explanations. Taken together, or set against a sensitive negotiation, dispute or leak, they are good reasons to consider a check.

• Someone knows details they should not, such as figures, plans or remarks made only in a closed meeting.
• An unfamiliar item appears after visitors, cleaners or contractors have been in: a new charger, clock, smoke detector, adaptor or ornament.
• Furniture, ceiling tiles, wall plates or light fittings have been moved slightly, or there is fresh dust or debris beneath them.
• Sockets, switches or fittings look newer than those around them, or screws show signs of having been turned.
• Office or home devices behave oddly, for example a desk phone that clicks or a television that switches itself on.
• A gift or promotional item arrives that seems designed to sit in your office or meeting room.

Context matters as much as the sign itself. An odd fitting in a busy reception area means little; the same fitting in a boardroom used for a pending acquisition deserves a closer look. Think about who would gain from listening, and when.

What should you avoid doing?

The instinct is to act at once. A few restraints protect both you and the chance of finding anything.

1. 01

   Say nothing in the room

   Do not discuss the suspicion, or the plan to have a sweep, anywhere you think may be monitored. That includes the car if you have concerns about it.

2. 02

   Call from somewhere else

   Arrange any help from a different phone, away from the premises, so the request itself is not overheard.

3. 03

   Do not search and dismantle

   Taking apart sockets, fittings or furniture is unsafe around wiring, can damage the property and may destroy what an examiner needs to see where a device was placed and how.

4. 04

   Keep routines normal

   A sudden change, such as moving every meeting elsewhere, can warn whoever placed a device that you are on to them.

If you believe you are in physical danger, contact the police first. A sweep is not a substitute for personal safety advice.

How does a sweep work?

A sweep, sometimes called technical surveillance countermeasures (TSCM), combines two methods. Each finds things the other can miss.

1. 01

   Discreet planning

   The rooms that matter, the times they are quiet and how the team will arrive are agreed away from the premises.

2. 02

   NLJD sweep

   A non-linear junction detector (NLJD) reacts to the semiconductor components found in almost all electronics. It is passed over walls, floors, ceilings and furniture, and it can find a hidden device whether or not it is switched on.

3. 03

   Physical inspection

   Examiners look into and behind fittings, sockets, ceiling voids, furniture and objects, checking anything the detector flagged and anything that looks out of place.

4. 04

   Findings and next steps

   Anything found should be photographed and recorded where it lies before it is touched, which matters if you later want to establish who placed it.

A sweep takes the rooms as they are in normal use, so leave things where they usually sit. Tidying beforehand can move or hide the very item that was out of place.

Phones and laptops raise a different question. Spyware on a phone is not found by sweeping a room; it needs an examination of the device itself.

What does a clear result mean?

A sweep describes the rooms at the time they were inspected. It cannot say what will be there next week, so you may prefer to arrange checks before particular meetings rather than once.

If nothing is found but information is still leaking, the cause may be human: a forwarded email, a careless conversation or someone with legitimate access. That calls for a different kind of enquiry.

Discretion matters from the very first call. We can sign a non-disclosure agreement (NDA) on request, and initial consultations are without obligation; charges apply only once work begins. Booking a sweep before a known sensitive meeting is often simpler than reacting afterwards.

Terms in this guide

• TSCM
• Non-linear junction detector (NLJD)

Questions