I'm not only interested in how they found out but when did they find out he didn't attend the conference but was spending their time and their dime with TH at another location....JMHO..
To me, it is interesting that he took that chance.
I imagine that his whole staff was watching his every move after they found out his wife was missing. Some may have known or had a feeling he was having an affair with TH prior to Gail's disappearance. I could be wrong on this, but I've worked in offices and rumors do get around sometimes. JMO