How did Goodkat know who Lindsey was at the time she snapped his photo?

I'm not quite sure it's appropriate to go the "I'm a world class assassin" route here, though it's possible.

I don't even think Slevin knew who Lindsey was when she first knocked on the door. That is, she was never a part of the initial plan to be involved. You can even tell the first time Slevin opens the door, he braces himself a bit thinking it's going to be Elvis and Sloe (then of course he is caught off-guard the next time because he thought it was Lindsey again).

Now, this whole time Goodkat at the hotel, meeting up with The Boss and The Rabbi, etc. He's not keeping tabs on Slevin in this way. I suppose it is possible that during the night of the dinner he scouted them out, but I just feel like that he knew her by the time she took his picture in the elevator (which I believe was when he was meeting The Rabbi?). Now even if he did know her by then, he also would have had to know she was "his girl," either from the dinner date and/or him staying over at her place that night.

Any ideas where he would have seen them that I'm missing?

** Rest in peace, Timothy Volkert (1988 - 2003) **