Frankly, discovering plagiarism is easy. All one has to do is type a sentence into google.
Furthermore, this student has been in this country for less than a year. The sudden "improvement" in his syntax was . . . shall we say . . . an alarm ringing.
What makes matters tough for me is this is a highly intelligent person.
The last student to plagiarize gave evidence of serious problems. She registers for classes then fails to show up. Whether her life story is true or not (English teachers learn intimate details!), I can not say. I, for one, do not trust that kid.
This one is a little different. He is one of two brothers who take the class together. They seem very nice, although this one, the older brother, is a tad manipulative. (I should say he stands 6' 4" and has movie star looks. The manipulativeness comes with the territory of the physically blessed.)
What happens is totally up the individual professor. Generally, the student receives an "F" for that assignment, which is what I did in both cases.
I also included with the student paper a copy of the source and a copy of the college's policy on plagiarism.
My hope is that this boy will take it as a wake up call. He has done nothing of the sort in my class before. As his other class is calculus, there is no opportunity for plagiarism there.