Last Updated: March 2026
What Methods Are Used in Infidelity Investigations?
Infidelity investigations in British Columbia typically use a combination of surveillance, background checks, open-source intelligence (OSINT), polygraph examinations, and digital forensics. The methods chosen for a particular case depend on what the client already knows, the nature of their concerns, and which approach is most likely to produce useful results within a reasonable timeframe and budget.
No two cases are identical. Some are resolved through a single focused surveillance period. Others require layering multiple methods, starting with background research to identify key details, moving into surveillance to document behavior, and potentially incorporating a polygraph or digital forensic examination to address specific questions that observation alone cannot answer.
This page explains how each method works in practice, when it is most effective, and what clients should expect.
This guide is published by Shadow Investigations Ltd., a licensed private investigation firm based in Vancouver, BC, serving British Columbia since 1990.
On This Page
- How Is Surveillance Used in Infidelity Investigations?
- How Do Background Checks Support an Infidelity Investigation?
- What Role Does OSINT Play in Infidelity Investigations?
- When Is a Polygraph Examination Used in an Infidelity Case?
- How Does Digital Forensics Apply to Infidelity Investigations?
- How Does an Investigator Decide Which Methods to Use?
- What If the Client Has Very Little Information to Start?
- Why Does Method Selection Affect Cost and Results?
How Is Surveillance Used in Infidelity Investigations?
Surveillance is the primary method in most infidelity investigations. It involves a licensed investigator physically observing and documenting the subject’s movements, activities, meetings, and public interactions over a defined period. When surveillance is productive, it provides direct, real-time evidence of what actually happened, not assumptions, not secondhand accounts, but documented observations with photographs, video, timestamps, and detailed investigator notes.
What Does a Surveillance Period Look Like?
A surveillance period is a block of time during which the investigator is actively monitoring the subject. In infidelity cases, a typical period might run four to eight hours, though the actual duration depends on what the investigator observes, as surveillance is objective-driven, meaning it continues as long as meaningful activity is unfolding and wraps up when observations have reached a natural conclusion. The investigator positions themselves to observe the subject’s departure from a known location, usually a residence or workplace, and follows their movements from there.
Surveillance can be static (observing from a fixed position, such as watching a residence or a location the subject is known to visit) or mobile (following the subject as they travel between locations). Most infidelity cases involve a combination of both. The investigator may begin with a static position outside the home, shift to mobile surveillance once the subject leaves, and return to static observation at whatever destination the subject arrives at.
What Makes Surveillance Succeed or Fail?
The single biggest factor in surveillance success is timing. Surveillance is most productive when the client can identify specific windows of concern, such as an evening the subject claims to be working late, a weekend trip that does not add up, a recurring pattern of unexplained absences on certain days. When the investigator knows when suspicious behavior is most likely to occur, they can plan the surveillance period to cover that window efficiently.
Surveillance becomes less efficient when there are no identifiable patterns and the investigator is working from general suspicion. In those situations, the case may require multiple periods before useful activity is observed, or it may benefit from background research or OSINT first to narrow the focus.
Other factors that affect surveillance outcomes include:
- Whether the subject’s vehicle is known and identifiable
- The geographic area involved, as urban environments with traffic and density present different challenges than suburban or rural areas
- Whether the subject is surveillance-conscious or likely to be cautious about being followed
- Weather and lighting conditions, which affect both observation and photographic documentation
What Happens If the Subject Does Not Do Anything Suspicious?
This is a common and important question. A surveillance period that does not capture suspicious activity is not a failure, it is still a documented result. Knowing that the subject went where they said they would go and did what they said they would do has value, particularly if it helps the client either put concerns to rest or recognize that a different time window should be investigated.
In some cases, several surveillance periods may be needed before a pattern becomes clear. Infidelity-related behavior is often intermittent and does not always occur on a predictable schedule.
How Do Background Checks Support an Infidelity Investigation?
Background checks provide context that makes other investigative methods more focused and efficient. They are rarely the primary method in an infidelity case, but they often play a critical supporting role, particularly when the client suspects a specific individual is involved or when additional background information on persons of interest is needed.
A background check in an infidelity context might involve researching:
- A suspected third party’s identity, address history, or known associations
- Business ties or shared interests between the subject and another individual
- Vehicle registrations or property records that may be relevant
- Public records that help confirm or refute a specific claim the subject has made
Background checks are often most useful at two stages: before surveillance, to help the investigator know what to look for and where to focus; and after surveillance, to identify or verify individuals, locations, or connections that were observed during fieldwork.
For example, if surveillance documents the subject visiting a particular address repeatedly, a background check can help determine who owns that address and whether there is a connection that warrants further investigation.
What Role Does OSINT Play in Infidelity Investigations?
Open-source intelligence (OSINT) involves gathering and analyzing information from publicly available sources, primarily online. In infidelity investigations, this means reviewing content that anyone could access, including public social media posts, publicly visible profiles, business directory listings, publicly accessible photographs, check-ins, comments, and other digital footprint indicators.
OSINT is not hacking. It does not involve accessing private accounts, bypassing passwords, or viewing content that the subject has restricted to a limited audience. It only covers information that is genuinely public.
When Is OSINT Most Useful?
OSINT tends to be most valuable in infidelity cases in the following situations:
- Identifying a suspected third party when the client has limited information—sometimes a name, a workplace, or even a general description is enough to locate a public profile that helps confirm or narrow the focus
- Establishing or challenging timelines, as public posts, check-ins, or tagged photographs may show where someone was at a particular time, which can be compared against what the subject claimed
- Identifying associations between the subject and another individual through public interactions, mutual connections, or shared activity
- Providing additional context before surveillance begins, so the investigator has a clearer picture of the people, places, and patterns involved
OSINT is rarely sufficient on its own to resolve an infidelity matter. Its strength is in supporting surveillance and background checks by filling in gaps, confirming leads, or identifying details that make fieldwork more targeted.
When Is a Polygraph Examination Used in an Infidelity Case?
A polygraph examination is a controlled, structured interview conducted by a trained polygraph examiner that measures physiological responses, including heart rate, respiration, blood pressure, and skin conductivity, while the subject answers a series of specific questions. In infidelity cases, a polygraph offers a more direct approach than surveillance: rather than observing behavior over time and drawing inferences, it addresses the core question head-on.
In What Situations Is a Polygraph Appropriate?
Polygraph examinations are most commonly used for infidelity matters in two scenarios:
- The client wants a direct answer to a specific question, such as whether their partner has been sexually or romantically involved with another person, and surveillance either has not produced a clear result or would take longer and cost more than the client is willing to invest
- The subject voluntarily offers to take a polygraph to demonstrate honesty or to help resolve a dispute, and both parties agree to the process
In some cases, the suggestion of a polygraph alone changes the dynamic of the situation. A subject who is being deceptive may decline or become evasive when a polygraph is proposed, which itself can be informative even if the examination never takes place.
What Should Clients Understand About Polygraph Results?
Polygraph results are not admissible as evidence in court in most Canadian jurisdictions, including British Columbia. This means a polygraph is not a tool for litigation, it is a tool for personal clarity. Clients use polygraph results to make informed decisions about relationships, separation, counselling, or trust, but they should not expect the results to carry legal weight in a family law proceeding.
A polygraph is also not a replacement for surveillance or other investigative methods. It answers whether the subject is being truthful about specific questions, but it does not document behavior, identify third parties, or produce the kind of photographic and video evidence that surveillance provides. In some cases, a polygraph and surveillance complement each other effectively, as surveillance documents what happened and the polygraph addresses the subject’s account of it.
How Does Digital Forensics Apply to Infidelity Investigations?
Digital forensics involves the examination of electronic devices, such as phones, computers, tablets, external drives, or other storage media, to recover and analyze data relevant to the investigation. In infidelity cases, this can include deleted text messages, call logs, chat app histories, email correspondence, photographs, videos, browsing history, location data, and app usage records.
Digital forensics can reveal information that surveillance and OSINT cannot reach. Surveillance documents public, observable behavior. OSINT covers publicly available online content. Digital forensics accesses private data stored on a device, including content the subject may have deleted or attempted to hide.
When Can Digital Forensics Be Used?
Authorization is the threshold issue. A digital forensic specialist can only conduct digital forensics on a device where the client has legal ownership or authorized access. This means the client must either own the device outright, co-own it, or have the explicit consent of the device owner. A digital forensic specialist cannot examine a phone, computer, or tablet that belongs solely to another person without that person’s knowledge and consent.
Common scenarios where digital forensics may be appropriate include:
- The client owns or jointly owns a phone or computer that the subject uses, and the client authorizes the examination
- The subject has voluntarily consented to a device examination as part of resolving a dispute or rebuilding trust
- A shared family computer or tablet contains data relevant to the investigation, and the client has ownership rights
- The client’s own device contains relevant data, such as messages received from the subject, that the client wants professionally preserved and documented
What Can Digital Forensics Recover?
The scope of recoverable data depends on the device type and model, its operating system version, how recently data was deleted, and whether the device has been reset. In general, a forensic examination may recover:
- Deleted text messages and chat conversations from apps such as iMessage, WhatsApp, Signal, Telegram, Facebook Messenger, and others
- Call logs and contact records, including deleted entries
- Photographs and videos, including those removed from the device’s visible gallery
- Location history and GPS data from mapping apps, photo metadata, or device-level tracking
- Browsing history, bookmarks, and search queries
- App installation and usage history, including dating apps or messaging platforms the subject may have used and later removed
- Email content stored locally on the device
Not all data is recoverable in every case. Realistically, most modern smartphones offer a reasonable window of approximately 30 days for recovering deleted data. Beyond that, results can be inconsistent, particularly if the storage space has been overwritten by new data. Encrypted or physically damaged devices may also yield limited results. A forensic examiner can usually assess the likely scope of recovery before a full examination is performed.
How Does Digital Forensics Relate to Other Methods?
Digital forensics is typically a later-stage method. It is most effective when there is a specific reason to examine a device, for instance when surveillance has confirmed suspicious behavior and the client wants to understand the full extent of the communication behind it, or when a subject has agreed to a device examination as part of a resolution process.
It can also be used independently when the client’s primary concern is digital communication rather than physical behavior, for example when the subject’s conduct occurs primarily through messaging or dating apps and there is little observable activity to surveil.
How Does an Investigator Decide Which Methods to Use?
Method selection is a strategic decision based on what the client knows, what they need to find out, and which approach is most likely to produce results efficiently. It is not a checklist, it is a judgment call informed by the specifics of the case.
The investigator considers factors such as:
- Whether there are known times, locations, or patterns of concern, as if so, surveillance is usually the starting point
- Whether a specific individual is suspected, as if so, background checks may help uncover additional information about that person to better inform the planning process
- Whether the subject’s behavior is primarily physical (going places, meeting people) or primarily digital (messaging, app-based communication), as this determines whether surveillance or digital forensics is the better lead method
- Whether the client wants direct confirmation through a polygraph rather than direct observations through surveillance
- The client’s budget and timeline, as some methods produce faster answers at different cost points
- Whether the case is likely to intersect with a legal matter, which may affect what types of documentation are most useful
In some cases, the investigation begins with one method and adapts as information develops. A surveillance period may reveal a location that triggers a background check. A background check may identify an individual whose online presence is then reviewed through OSINT. A polygraph may be proposed after surveillance produces ambiguous results. The methods work together, and an experienced investigator adjusts the approach as the case evolves.
What If the Client Has Very Little Information to Start?
Cases can still move forward with limited information, but the approach and expectations may need to be adjusted. When the client has very little to go on, such as no specific times of concern, no suspected individual, and no identifiable patterns, carefully considering all available options helps ensure that investigative resources are used as effectively as possible.
In low-information cases, the investigation may benefit from starting with:
- A background check on the subject to identify patterns, associations, or addresses the client may not be aware of
- OSINT research to review public digital activity for leads or timeline indicators
- A detailed intake conversation to extract details the client may not have realized are relevant, such as changes in phone behavior, new apps, altered routines around specific days, or financial transactions that suggest undisclosed spending
Once enough context exists to identify productive surveillance windows, sometimes through a process of elimination by ruling out periods when the subject is known to be with the client, family, or at work, fieldwork can be planned around the times that present the most opportunity. This staged approach often costs less overall than starting with broad, unfocused surveillance such as 12 hours per day for a week.
The most useful information a client can provide at intake includes:
- The subject’s full name, age, and physical description
- Vehicle details including make, model, colour, and license plate number
- Home and work addresses
- Regular daily schedule and known routine
- Specific dates, times, or events that prompted concern
- The reason the client believes something is inconsistent, as even vague concerns sometimes contain useful investigative leads when discussed with an experienced investigator
Why Does Method Selection Affect Cost and Results?
Choosing the right method for the right situation directly affects both what the investigation costs and whether it produces useful results. A well-planned case that starts with the most appropriate method typically resolves faster and at lower cost than one that applies a generic approach.
For example:
- A client with a specific night of concern and a known vehicle may only need a single surveillance period to document what happens, which is a focused, cost-effective approach
- A client with broad suspicion but no specific leads may benefit from starting with background research and OSINT before committing to surveillance hours
- A client who wants a direct yes-or-no answer about a specific allegation may find a polygraph examination more efficient than surveillance
- A client whose spouse conducts their relationship entirely through their phone may get more value from a digital forensic examination than from physical surveillance
During intake, the investigator assesses which combination of methods is most likely to address the client’s concerns while directing resources toward the approach with the highest likelihood of producing meaningful results.
Related Knowledge Pages
- Infidelity Investigations in BC — Main Page
- How Much Does an Infidelity Investigation Cost in BC?
- What Are the Legal Considerations for Infidelity Investigations in BC?
- What Evidence Can Be Gathered in an Infidelity Investigation?
- Infidelity Investigations in BC — Frequently Asked Questions
Related Articles
- Methods of Investigating Infidelity
- How Surveillance Investigators Obtain Evidence Undetected
- How to Catch a Cheating Spouse: Case Setup Guide
Need Help Deciding Which Approach Is Right?
If you are considering an infidelity investigation and are unsure which methods may apply to your situation, contact Shadow Investigations by phone at 604-657-4499 or through our confidential inquiry form. We can assess the circumstances, recommend an approach based on what you already know, and explain what to expect before any work begins.
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