Did they delete their facebook?

So today i was looking at one of my pictures and I noticed that all of someones comments were gone. I went on my wall and noticed that their post wasn't there, so i typed in there name and found them. When I clicked th Add as Friend button it said Ooops something is wrong. Is that because they recently deleted it? I also checked 2 of my other friends pages and noticed that they both were missing 1 friend (they had been friends with each other) Just wondering.