Teaching Assistants (TAs) play a critical role at the University in creating an academic environment that promotes academic integrity, as well as frequently being one of the first to detect any breaches of integrity. The following links are to resources with guidelines on how to encourage and detect instances of AI offenses.
If you, as a TA, suspect of plagiarism or other breaches of academic integrity with student(s) in your course, report to your course instructor right away. S/he will be responsible in communicating with the student involved as a set of standard policies exist for such issues.
Keep in mind these articles are written for different universities and the appropriate policies may not apply.
Talk to your course instructor at the beginning of the semester to discuss about AI, or refer to Academic Integrity Procedures - Requirements for Faculties & Schools for more information.