Non native speaker?

[Duane Campbell]

According to published reports, the notes left by the sniper are in an
imperfect English indicating perhaps a non-native speaker. Yet the one
sentence they have released -- "Your children are not safe at any time or
in any place." (from memory) -- strikes me as a very well crafted
sentence. Not just lucid and free from error, but stylish.

Any forensic linguists on the list? Is there such a thing as a forensic
linguist?

While I'm asking questions, Chief Moose (who is, incidentally, Dr. Moose)
replaces all of his "th" sounds with either a hard "D" (initial) or "F".
I have heard this from time to time, though usually not so pronounced,
including a classmate in 1950s rural Pennsylvania with a 100 percent
white school population. I had always assumed it was a minor speech
impediment (is there a new PC word for this?) or an ideomorph. Are there
dialects that include this shift?

D