How weird

Watching the episode "Lawson's Last Stand" and this scene always has me wondering.



This clearly shows Lawson leaving the institute and apparently no-one sees him leaving but yet there is someone watching in the window.




Then Doyle asks if this was where he went out and did anyone see him from the outside to which the doctor answers no but someone did see him leave so why wasn't it reported.The only thing i can think of is that the person watching could be another patient.