B, one of the scams I read about, uses a patsy to accept checks from other romance victims, cash them and send the money out. Another variation on that is even worse. The person is pulled into the con, loses a lot of money, and then makes arrangements to cash the checks and send the money and gets a commission for doing it so that they get their money back.
That post is about 10 days back, and not everyone comes to check here for replies. Who is Muriel Fisher? Where from>? And what is she doing or has she done that has you concerned? Post back and maybe we can find something on this site that will be of use. If you reply here, I will find it.
I don't have specific details, I just know that "she's" been talking with him for well over a year, and has him convinced that she's coming to see him in the states. He won't tell me much, because she has him brainwashed, and I'd like to convince him to stop talking with her.
You might try a google search on "Romance Scams". I seem to recall that there are websites where people compare info and details on various scams and scammers. Most of the serial scammers tend to use the same or very similar names for some reason, and that helps.
Has she asked for money yet? Sent via Western Union or something equally untraceable? Do you know if this is coming from Nigeria or Russia? One way you might bust the scam and get your father to believe you is to see if you can find a photo she has sent. Then run the photo through Google Image Search and see if it pops up in other contexts and places. The scammers will grab photos from FB or even stock photo sites, and if you can show you dad that lie, you start to get an edge.
If you know how they got in contact that can help too. You can sometimes go to websites like POF or Match and create a profile that is like you dad's, and see if you get a nibble from the same scammer.
You are going to find out some ugly stuff about this crooked world, and maybe about your own father. But these scammers are ruthless, and this is BIG business for them. If you are worried, you need to put you mind at rest and to protect your dad. If you do bust the crook, you need to be able to take care of dad. Part of him will be angry, but part of that will be anger at himself, and that can lead to some dark nights of the soul for anyone who realizes they have been played for a fool. Be Strong, Stay Safe.