Disclaimer: I am not a lawyer & this is info I have found by googling.
Here's a form for Oklahoma (which is where I think you will have to file since that was the last known location for him) for a Petition for a Letter of Administration (link & attachment of document are below).
I am not sure that is the exact form you should use. The last place (I think) where you have listed that he was seen was in Claremore, Oklahoma which is in Rogers County. I would perhaps call the court clerk of Rogers County & ask if this is the form you would use & if you would file it with their court. If not, she could maybe point you to the right location or form.
View attachment 481223
Part of OK law (part 58-941)
Also, fyi, here's the part of OK law about the letters of administration (part 58-943). It's not quite the same as having someone declared legally deceased but it does deal with someone who has been absent for 7 years & for a person wanting info on the estate, so maybe this is a way to start to find out the process:
And I'll add this link again even though I had it in my previous post too. I think it gives a clear step-by-step process which is probably close to the process you will need to follow, imo.
When a person has been missing, you can sometimes petition a court to declare the person dead. The process will vary depending on the country where you live. In the United States, the process will differ depending on the state in which the...
www.wikihow.com
Hugs,
@Snoangel26. You've walked a long road & I know this isn't the outcome you hoped for. Hang in there. You have friends here & people to lean on.