Followed in my car, Odd stranger taking video of me at dinner - Common?

[Blueberry Pancakes]

This is about behaviors I think were coming from my sister's husband, and wondering if this is common or over-the-top?  I never told anyone about this. Actually when I write it down, I think it makes me sound a bit nutty. Anyway, I hope someone here might understand.   
   
I am no contact with my sister and her husband for three years. I think they both have behaviors that are consistent with NPD, and sometimes wonder if my BIL might even have some sociopathic tendencies. No diagnosis, just my own suspicions.
 
I was gaining increasing awareness of what was going on in my sister's marriage, and we had several conversations. I admit, I went into "fix it" mode a bit. I never confronted my BIL, and outwardly with everyone tried to remain neutral. This is the time I started noticing odd things.     
 
One time I drove home from my sister's house after visiting when my BIL was gone, and realized a car following very closely behind me. I live less than 10 miles away, but the car followed me at every single turn. When it followed me into my neighborhood I hit the brakes. A man was in the car on his cell phone, starring directly at me, stopped behind me. I was going to call police, but he did a U-turn and drove out of the neighborhood. I thought I was deliberately followed. A few other times I was at a restaurant and looked across the room and noticed a stranger holding up their cell phone in my direction and as I moved, they followed my motions. One even quickly put down the phone when I noticed them. I felt like I was being monitored. There were several times I had private conversations on my phone about events I never told anyone about, then my BIL would ask about it when I would see him. A few other times I was on the phone to a friend who is a lawyer asking about my concerns with all of this, then the phone call dropped and I had call back. I felt like the phone line was being tapped. 

I wondered if BIL saw me as a threat so he was having me monitored. I never confronted him, but instead silently backed off and am NC for three years. I ran into them a couple months ago, and BIL told me I owed him an explanation right on the spot or he was going to come over to my house and break the door down. I walked out, and so far no sign of him but it all leaves a chill in my bones that won't go away.  Thanks. 
     
   

[bloomie]

Blueberry Pancakes - this all sounds so unnerving. I am really glad you are paying close attention to your surroundings. I have experienced behind the scenes (not so outright and in my face like being followed like you were) stalking behaviors from one family member, but nothing like you describe here - the man following you and clearly not worried you saw him videoing you. So strange!

I am thinking, from your post, that the issues and concerns with your mobile device were in the past? If not, you could have your phone checked for spyware just to give yourself some peace of mind.

I remember your recent thread about your bil's confrontation and demands and ultimatum and threats are outrageous and over the line. You don't sound nutty and I am so glad you risked sharing. You sound traumatized and rightly hyper vigilant when you are out and about. I am so sorry.

[Hepatica]

Blueberry Pancakes - After the way he behaved, saying he would break your door down, he is definitely threatening. That is a fact. Because he uses threats, you have no idea what he is capable of. I mean you have to believe someone when they threaten. What sort of explanation was he seeking? He didn't like that you backed away? In any case, it all sounds scary.

I'd take your concerns seriously and do as Bloomie said, and get your phone checked. I would totally be feeling hyper vigilant.

I had a girlfriend years ago who invited me to her home for the weekend. She lived four hours away and I went. Her boyfriend was abusive and she told me everything and I was appalled. I left and her boyfriend made prank calls to me for a few months afterward. I think she told him that she had spilled the beans to me about his abuse to her and he was so threatened by me knowing, he tried to intimidate me. I remember feeling sick about it. It was like I got drawn into their dysfunction when I didn't want anything to do with it. It was very unnerving and I felt scared for a long time afterward. I understand why you're feeling the way you are. Trust your feelings and keep yourself safe. I think backing away is a very good idea. Major grey rock. It's sad that you can't help your sister, but she is a big girl and can seek help when and if she decides she wants it - and it should be professional help. She should not put you at risk.

[Andeza]

Trust your gut. If it feels wrong, it probably is.

I've driven past my turn for home before just to see if I was being tailed. I'm small, so I'm an appealing target. The extra gas is a small price to pay for peace of mind. If you are ever tailed, drive to the police station while letting them know you're on your way.

In our current home, we have a screamer on the door, along with a security system that videos the door on the outside. In a previous home, we had a solid core door with door armor, window screamers, and other fun things because we lived in a bad neighborhood. If any of those things appeal to you, check them out. All of them were homeowner friendly and easy to install. No handyman required.

[BeautifulCrazy]

Absolutely trust your gut!!
I don't think you sound nuts at all.

If he is like that around you, how scary / crazy could he be to those closer to him, or someone who actually did something to cross him?

If it were me, I wouldn't hesitate to go to the police.
If it turns out to be nothing, no harm done.
If it turns into something later on, or needs action, you have already started an evidence trail. (This could help you, someone experiencing similar, your sister etc.)

Worst case good scenario, you look a bit nuts.
Worse case bad scenario, he gets away with extreme escalation before consequences happen because nobody ever bothered to say anything.

I deeply regret not saying anything about this sort of behavior when I encountered it in the past.

[Blueberry Pancakes]

Thank you Bloomie, Hepatica, Andeza and BeautifulCrazy. You offer great suggestions about having my phone checked for spyware and some alarms I can install around my house.  I started looking into alarms and I agree, there are some that look amazing easy to install.

I think you may also be correct about feeling traumatized. Being NC for three years has been hugely beneficial for my wellbeing, but I think unexpectedly running into them a couple months ago and the confrontation that ensued stirred up some feelings that I realize still remain. Thank you for being on this forum, sharing your own experiences and offering such helpful insights.