The USCIS has the discretion to suspect and subsequently investigate a marriage that may bring immigration benefits to analien. If the USCIS has reasons to suspect that the marriage is a "sham marriage", the USCIS officers have the authority to investigate. Usually, the USCIS officers may visit the suspect couple at their residence, or visit their neighbors to investigate whether they reside together, share a household, or own property jointly, etc. The USCIS officers may also arrange interviews with the couple at their residence or at USCIS offices. In the interview, the USCIS officers may ask private questions regarding all aspects of their marital relationship, such as the brand of the other spouse's underwear or the favorite food, except those which are too intrusive, such as sexual habits.

In order to prove that the marriage is not a sham marriage during the interview, the couple would be better off preparing the following materials:

1. Wedding photos and other pictures taken together;
2.  
3. Records including telephone bills and mail correspondence showing their relationship over a reasonably long period of time, including prior to the marriage;
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5. Evidence of property owned jointly by the couples, such as a joint bank account under both parties names or a deed documenting real property ownership.
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7. A lease or other records evidencing that the couple live together;
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9. Joint tax return forms submitted to the IRS; or
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11. Any other documents that may prove the marital relationship.