Foul play suspected! Help me investigate what happened!

What parent doesn’t wish to know they have a son who will drop everything to make sure that they are ok and not a victim of foul play.

First off, I love my dad. I may not have grown up with him around, but he’s always been there for me. Now that I myself am a father, his advise is golden to me. He is a buisness owner and divorced, and recently sold his house. He’s in his late 60’s, and a really nice man. Which makes him a perfect target. He has ALWAYS responded to my emails/calls. Now in august of 2019 I was going through the town where he lives, phone disconnected. So I sent an email to his business gmail account. I get a reply from his “partner” saying he wont be in contact for “quite some time” as he is on a remote hiking trip. Uh huh, he has a replacement knee. And his “partner” refused to give me his cell number when asked. That is not like him at all! So months go by and I get no replies to repeated emails. Then a couple months ago I had enough, I sent an email saying “Dad if you dont get ahold of me i’m hoing to contact the authorities to find you!”. I got response in 20 minutes berating me on how offensive I was for such a rude email. That wasn't him. He would NEVER lash out at me because I’m concerned. So I said i'm sorry “dad” please call me so i can make sure you're ok. No reply since.

I need to go to Oregon and find my dad! I don't have the resources to afford this trip from southern california to oregon. If I cannot find him then I will go to the authorities and start a manhunt. My half-brother is estranged from him. But this partner whom ever it is, didn't know about his first son, me. I dont think anyone is looking for him except me!! That has got to change!! Help a concerned son make sure his dad is ok.