I think there has to be someone talking based on the specific area that they were searching in Hartford. I also think that obtaining the search warrant made the STBX and his gf begin a conversation with the police. I kind of like how the LEO has been playing their cards. You are not in custody and drive your own car to the station, pack a bag, but, we will be going over your home with a fine tooth comb.
I have a couple of questions though. Did they get a warrant to look at his car? (If not, do they think another vehicle was used or her vehicle was used to dispose of her- assuming she is dead?) Or, the gf's car? (If no, then we can assume they have evidence that the car was not used.) Was he driving a rental because they already have his car? Did LE ask for a warrant for his business offices? Or, other business vehicles?
I think Jennifer will be found in a short frame of time.