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6 Ways Private Investigators Can Prove Cohabitation

Editor's note: This article was written by Scott Fulmer of Intermountain PI about cohabitation investigations.The opinions expressed here belong to Scott Fulmer.

Private investigators conduct cohabitation investigations to prove that a client’s ex-spouse is living with someone, thereby allowing the client to adjust or terminate the amount of alimony they are paying.

Cohabitation Investigations

What is Cohabitation?

First, let’s begin with a clear definition. Cohabitation is simply the act of two people living together in a sexual relationship without being married. Of course, what constitutes cohabitation is different depending upon the state in which you live. In Utah, cohabitation may affect alimony, also known as spousal support. In some instances, it may even affect child custody arrangements. During the final analysis, the court determines whether or not spousal support is granted, the amount granted, and how long the spousal support will continue. Additionally, the court may take infidelity into consideration or other matters that contributed to the divorce. Either way, it can be a lengthy and complicated process where consulting a divorce attorney is recommended.

Let’s look at an example. You and your spouse decide to divorce due to irreconcilable differences. The court stipulates that you are to pay your ex-spouse several thousand dollars a month in spousal support. The court considers many factors when coming up with the actual amount of alimony. Regardless, in Utah, spousal support can only be terminated or adjusted for a few reasons.

  • Death of the Recipient: In our example from above, if your ex-spouse dies (or you die) then you no longer pay spousal support.
  • Remarriage of the Recipient: If your ex-spouse remarries, then spousal support can be terminated.
  • Cohabitation of the Recipient: If your ex-spouse begins living with someone in a sexual relationship without being married, you may petition the court to adjust or terminate spousal support.

As a reminder, the above examples refer to cohabitation within the state of Utah. The laws in other states may differ. For example, in Colorado, the act of cohabitating is not, by itself, necessarily grounds to end or even modify the amount of alimony someone is paying. Before conducting a cohabitation investigation, it is imperative that you familiarize yourself with the state laws in your area.

Proving Cohabitation

Knowing someone is cohabiting and proving it are two entirely different things. Unfortunately, proving cohabitation may or may not end your obligation to pay alimony. The court has the final say. For this reason, proving cohabitation in Utah requires a private investigator to demonstrate that the ex-spouse is living in what the courts call a spouse-like relationship. With this in mind, I recommend a careful reading Haddow v. Haddow, the 1985 Utah case decided by the Utah Supreme Court. Typically, proving cohabitation involves about three factors. Continuing with our example from above:

  • Your ex-spouse and partner live in the same residence
  • Your ex-spouse and partner are in a sexual relationship
  • Your ex-spouse and partner share expenses and demonstrate joint decision-making

Of course, there are other factors to consider:

  • Length of time your ex-spouse and partner have been living together
  • Sharing of parenting duties
  • Evidence your ex-spouse’s financial situation has changed as a result of the cohabitation

With these factors in mind, how does a private investigator prove cohabitation? I’ve outlined six steps to proving cohabitation. Bear in mind, a typical cohabitation investigation can take three to four weeks and cost at least a couple of thousand dollars or more.

6 Ways Private Investigators Can Prove Cohabitation

  • Surveillance
  • Public Records
  • Social Media
  • Trash Pull
  • Statements
  • Background Investigation

Combined, these six steps work together to provide a six-legged stool that supports cohabitation. Let’s consider each specific step in detail.

1. Surveillance

Surveillance is utilized over the course of three to four weeks to aid in proving cohabitation. We are looking for the routines that are part of all of our lives. That means video evidence of the ex-spouse and partner coming and going to the residence including video evidence of them using keys and garage door openers as well as parking in the driveway and garage.

Additionally, useful video evidence includes documentation of the ex-spouse and partner engaged in yardwork, house maintenance and retrieving mail from the mailbox. The storage of tools, boats, trailers, and other items owned by the partner should also be documented. Public displays of affection between the ex-spouse and partner are an added bonus.

2. Public Records

The second leg of our six-legged stool of cohabitation is a search of public records. This may reveal shared utility accounts or vehicle ownership.

3. Social media

Speaking of shared accounts, does the ex-spouse and partner share social media accounts? Even if they don’t, be sure to document their social media posts of shared activities and shared vacations.

4. Trash Pull

A trash pull can be a veritable goldmine of information when it comes to proving cohabitation. The more evidence you have the better your client’s chance in court.

You may find many useful items in a trash pull including notes, letters, and other documentation suggesting a spouse-like relationship. Prescription bottles and banking paperwork may indicate shared accounts. Just keep in mind that going through someone’s trash is generally only permissible only once it has been taken to the curb and is no longer the property of the owner.

5. Gathering Statements

How does the neighborhood view the relationship? Interview neighbors and others in the community. They may be able to shed light on how the relationship between the ex-spouse and partner is viewed. This should be done at the end of the investigation as it will no doubt get back to the ex-spouse.

Has the couple gone on vacation together? Be sure to track down where they stayed. You might be able to gather statements from hotel and resort staff stating that the couple were in the same room and engaged in public displays of affection.

6. Background check

Finally, a background investigation of the ex-spouse’s partner may also reveal problems. While it may not prove cohabitation, it could help in the child custody area.

In the end, only the court can determine if an ex-spouse and partner are living in a spouse-like relationship. Moreover, it is also up to the court to adjust or terminate alimony. Like most things in life, there are no guarantees. But with these 6 steps, a private investigator can make a serious effort to advise the court of changes in the ex-spouse’s living arrangements.

About the Author

Scott Fulmer

Notable private investigator Scott Fulmer is the principal and lead investigator at Intermountain PI, the premiere private investigation firm throughout the Intermountain West. Scott is a 30-year veteran private investigator, host of the Intermountain PI Podcast and author of the critically acclaimed true crime memoir, Confessions of a Private Eye. It’s available on Amazon and Barnes and Noble. Find him on the web at

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