Yes. Probably not surprise that the postdoc was a PRC national. Very competent in their field of study, but also in this country with instructions from an APT group.
Less than a year later a story made national headlines that a professor with direct access to classified material had mysteriously disappeared & never disclosed his close ties with their home country. So not only should you be worried about back doors and side doors; but also watch what's going through your front door as well!