What can one do if an elderly parent is being swindled out of substantial sums of money under the guise of a romantic relationship?

This is called a " sweetheart scam" Call the police and report this immediately, also pay the 30 dollars and do a background check on this person so you have something to show your suspicions are right. Most of all Always, always follow your gut feelings when it comes to Elders.

I see that your dad has diabetes. Your profile does not mention dementia or other cognitive impairments. So, if he is in his "right mind" he is entitled to associate with anyone he chooses and to spend his money as he sees fit.

Perhaps, deep down, he knows this is a scam, but he enjoys it so much he doesn't care. Digging up some dirt on this woman might or might not influence his behavior. You know him -- what do you think?

Maybe leaving the woman out of this entirely and making it a purely financial discussion would be more effective. If you can demonstrate that without any extravagant purchases such as a new car and without any major health problems his financial holding will support him for about x years at his current standard of living. If there are major expenses such as putting a new roof on the house, taking a fancy cruise, etc (you don't even have to mention gifts to this woman) then each of those reduces the length of time he can support himself.

If he has an illness that disables him and requires in-home care (or a care center of some kind) that will deplete his resources much faster.

Once his resources are gone he won't be eligible for Medicaid immediately because of having given substantial gifts. There will be penalties based on any gifts given within 5 years of applying for aid.

Do you think that you and your brothers could put together a financial-facts-of-life presentation for Dad, leaving out the girlfriend completely?

This situation is very similar to what our family is going through. My 90 year old widowed grandfather was befriended by a 54 year old woman that worked at the grocery store my grandparents regularly shopped. I would suggest the three of you sit down and have a non confrontation but direct conversation about the inappropriate relationship and the families wishes that she move on. Call adult protective services as well. Also, consider your dads mental and physical state. Guardianships are an option as well. Don't give up, these types of sweet heart scams are everywhere. Simply saying there's not much you can do is opening the door for these criminals. This woman ended up marrying my grandfather in secret, changing his whole estate plan three months later and he died a year after that. Now, we have found ourselves in the middle of a legal battle trying to prove undue influence. This has taken years and is very expensive. If there's anything you can do, do it. Be present in your dads life. Also, this 30 year old may have a boyfriend or someone else she's working with. Go with your instincts. Good luck, hopefully you will not have to endure the heartache of what my family has gone through.

It sounds like an Anna Nicole Smith scenario. There is not a lot you can do, most likely, except try to talk some sense into your father. You can also have a background investigation done on the woman that may turn up something. As morally wrong as it may be, there may actually be nothing illegal going on. You might try spending a lot of time with your father to try to cut down on the unaccompanied access of this woman to him. Good luck.