I personally think he checked himself in to the psych ward so that he could build a case for an insanity plea. It seems clever but it's a cheap trick that any judge or good jury will see straight through!
The fact that they found her hair in a garbage bin near the mattress store where her husband bought a mattress very soon after her disappearance/murder is also pretty damning to his case. Not to mention his lying about going to medical school and various other falsehoods. He seems a few bricks short of a load.
Things like this make me very sad.
