Strictly speaking, you don't know whether it's implanted or not, but Mark can see it moving, so unless it's become alive, it must be with Frozen Yoghurt. Also, the location Mark sent you and the commotion in the crowd are identical.
I guess, FY has to find something
really clever to escape you now... You know where he is, you can trace him via matrix and astrally, he's easy to perceive and, well, he's nude.
EDIT:
@gilga
Every fifteen minutes after you first start tallying an OS, it increases by another 2D6 (rolled by the gamemaster in secret).
So, in the meanwhile it would have increased by 4d6 (plus ever hits in opposed rolls).