What if a guy stares and doesnt talk?

I am workin as an intern in a legal firm and we see lot of lawyers come to our office ..n now there's this stranger lawyer (because i dont know him personally ) who keeps on staring at me , with his puppy love eyes and this has been going on for two-three months , also he sometimes ignores me in front of his colleagues but stares intensely when alone and i just reciprocate his looks with staring at him from my side and smiling once or twice but now i am getting frustrated about what he really wants and it would be great help if you guys could help me out about what to do of this situation? I cannot approach him because i am an intern and it might affect my job...any subtle signs to give :p