Snoangel26 said;
"I reached out to PI company and asked if they could
run the ssn I have for Stephen. They did and told me
it came back to a different name and that the person
was still alive."
...
"The detective told me that his ssn hasn't been active."
Both statements could still be true, if the SSN hasn't
been used for years. There's the possibility someone
used it for false ID purposes in the last century...
say, to try and access veteran benefits or some such
thing. Alternatively, the information on the internet
is rather rubbery as to whether someoneelse can be
accidently issued a previously issued number... seems
like it might be a thing, although the false ID purpose
theory seems more likely.
Rather than bothering your local police about this,
which is really a Federal matter, I'd talk to whatever
Federal Law Enforcement agency you've been talking
to in regard to Stephen Murphy, (NCIS?) to report a
possible incidence of false ID usage of the SSN,
preferably getting the result of their enquiries in
writing. Then, if you ever have to go before a Judge
to assert that Stephen Murphy is believed to be
deceased, and the Judge happens to ask if his SSN
has been active, you'll be able to produce a document
from LE that shows that while the SSN has been used
since 1974, at least LE has determined that the person
who used the SSN is NOT your Stephen Murphy.