While universities have university-wide policies on plagiarism and academic integrity, individual departments may also have their own policies and procedures. As was the case with the TA below, you may have the responsibility of handling the situation.
I have had several students attempt to turn in others students’ work as their own. This hurts both parties involved. I usually catch attempts through the use of "Safe Assign" on BlackBoard. One student inparticular tried to turn in their spouse's nursing paper. Each department handles this situation differently and the dean ended up letting me decide how to handle it. Since I had assigned it as being a bonus to an exam, I called the student in and asked them about the paper. They broke down immediately and explained about the stresses at the end of the semester and that they really needed the points. I told them I understood, but could not grant them any points because it was not their work. I then explained how this may have been handled if it were a different class or a different assignment. The student was grateful that I was letting them off with a warning and said that they had learned their lesson. This seems to the general reaction when students are confronted with the evidence that they have plagiarized, but they sometimes are unaware of the consequences.