Is there anyway to verify if a person has had an interview at the American embassy in Moscow? Or if the application has even been processed? I have sent a letter of request and was told that the visa to visit the US is in process. Is there any way to verify this?
Unfortunately, no. The only source of information available to you is the visa applicant:
I would like to know if my friend has applied for a visa and what the status is. Who should I contact?
Your friend, the visa applicant. Under U.S. law, specifically the Immigration and Nationality Act (INA) 222(f), visa records are confidential. Therefore, the visa applicant should inquire at the U.S. Embassy or Consulate abroad where he/she applied regarding necessary information about visa application status. Because of confidentiality of visa records, you’ll need to ask your friend, the visa applicant your questions about whether a visa application was made, or a visa was issued or denied.