I doubt this is a premeditated murder. It's quite possible that something that happened at the meeting with the architect caused such a conflict that when they arrived at home he confronted her, he took off his belt and strangled her. After realizing what he did, he had a few choices:
- call police, report the "heat of passion" murder and watch his reputation as philanthropist transform overnight to nothing more than murderer,
- leave a note, confess to the murder, and commit suicide; or
- stage the scene to appear as a double murder to protect his reputation.
Early information is that she was killed in a different part of the house and moved the pool. With the belt around her neck, he could have dragged her to the pool area. General observations by forum members is that when the bodies were removed from the house, one was flat, the other was not. It takes about 36 hours for rigour mortise to leave the body. If she was killed on Wednesday evening, her body would be limp at noon on Friday. If he committed suicide closer to Thursday morning, he would still be stiff. This would be one factor to support the murder suicide theory.
Some have suggested that criminals may have been in the house, killed the wife, and then kept the husband alive for extortion purposes. That makes no sense because a threat against the wife is the leverage to force the husband to do something. If she's already dead, there is no leverage.