[FLUX-YOU]

I doubt a law firm would put their letterhead on a fake letter, but looking at the public map, most of the subdivision I got a letter for is already owned by the USA:

http://www.cameroncad.org/cadclientdb/propertymap.aspx

Tarpon Haven Subdivision

Edit: There's also two huge tracts of land above that subdivision that are also owned by the US. I'm not sure they even need to go through that subdivision if they wanted to just build a wall through the land the government already owns.

That's rather... ineffective.

[moonka]

Where did you find which property they bought? I probably missed it. I also imagine that if they built north of the property, walling off a part of property from the rest of the country in that fashion would fall into some legal issues.

[FLUX-YOU]

It was in the letter they sent to individuals: https://imgur.com/emSk75t