the relative has recently gone “missing”.
70 years old. phone disconnected, web site defunct.
Have the local PD where he/she lives/lived do a wellness check? I know, involving the cops may be undesirable. Is there anyone you know in the place where your relative last lived who may be able to check on their status in person? A local church, maybe?
Search local news in her town for her name for marriage or human interest stories. Local hospitals, local neighbors, if known. Did she have a trust? Is the trustee known? If you know where she banked you could try to contact the bank and ask them to relay message through the bank. (They will not acknowledge that she is a customer, but may agree to forward a note to her if found in their customer records.)
On the grim side, coroner and obituaries. If she had a will there would be probate records.
Lets hope that she just moved and got a new cell phone.
If any of this works let me know!