This a fairly common occurrence unfortunately. Thieves identify major hotels or conference venues where it will be impossible that the staff will know by sight everyone attending. They dress appropriately for the type of clientele, mingle for a while during morning tea break to observe, maybe make a fake name badge (even pick one up from the registration desk left there for a late arrival who hasn't shown up) and then at lunchtime, unless the organisers have been quite anal about having the room locked for the duration they brazenly walk in as if they're a delegate returning for some reason (the staff are usually thinned out serving lunch or refreshing the room), target any interesting looking bags, purses, computers, phones etc and calmly walk out with them in hand or on shoulder. Both men and women are involved and blend in seamlessly with the hotel or venue population. Sorry you got caught but it happens a lot more than most people realise and the Innkeepers Liability Act usually means you have no recourse on the venue. If you haven't insured your gear yourself you're cooked!