This series is really extraordinary, and this is an excellent episode. The logic is sometimes hard to follow (things move quickly from one step to another), but one assumes there is a logic: great deal of intellectual complexity.
But the "kicker"--what holds everything together--is the ending: the emotional conclusion. One may think that the character is "over the top:" to extreme; unbelievable. However, the ending makes sense, emotionally. A lonely man, trying to fill his empty house.
"Law & Order, Criminal Intent" is heads and shoulders above anything I've seen on television: so compelling. But then, I miss Manhattan (where I lived for 30 years) and love the street scenes.