1. Get Immigrant Visa at U.S. Embassy or Consulate

If a U.S. citizen marries an alien abroad, an I-130 petition must be filed after the marriage to begin the immigration process for the alien husband or wife. This can be filed with the U.S. Citizenship and Immigration Services in the United States.

The first step in applying for an immigrant visa is for the U.S. citizen to file an immigrant visa petition with a Service Center of USCIS. Each person immigrating will be required to complete a biographic data form DS-230 Part I. The appointment for the visa interview and medical examination will be scheduled. 

The Immigrant Visa Unit at U.S. embassy or consulate will process the application for an immigrant visa. While no assurance can be given regarding the appointment date of the visa interview, the alien spouse should prepare for that appointment and obtain the documents required for the visa application. 

2. The Form I-485 Adjustment of Status for Parents inside U.S.

The Form I-485 adjustment of status application is for an applicant who is in U.S. already on a non-immigrant visa. If the eligibility of your I-485 application is based on an immigrant petition, you need to attach a copy of the approval notice for an immigrant petition that makes a visa number immediately available to you. If your eligibility is based on the Form I-130 approval, you need to attach a copy of the Form I-130 approval notice.

The medical examination, endorsed by a civil medical doctor on Form I-693, Medical Examination of Aliens Seeking Adjustment of Status, is a necessary part of the Green Card application process.

3. A Suspect Marriage and Investigation of USCIS

The USCIS has the discretion to suspect and then accordingly to investigate a marriage that may bring immigration benefits to the aliens. 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. 

Also, the USCIS officers may 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 offensively intrusive.