He is being treated by a Doctor Who specialises in the criminally insane, which means Dave has committed a crime in the past and not been sent to prison for it because he pleaded 'Insanity'. This means the court said he was not guilty because he was insane (not in his right mind) at the time, and was sent to a mental instutition instead.
In Desperate Housewives, he has clearly been let out and since has met Edie, who does not know about his criminal past or monthly phonecalls with his psychiatrist.
the people on desperate housewives
Desperate Housewives is currently on season 7
"Desperate Housewives Theme" by Danny Elfman
If... - Desperate Housewives - was created on 2010-01-03.
Desperate Housewives was created on 2004-10-03.
It was either Richard Burgi (who plays Karl Mayer on Desperate Housewives) or Doug Savant (who plays Tom Scavo on Desperate Housewives).
American actress Tina Louise did not appear on Desperate Housewives
Bargaining - Desperate Housewives - was created on 2009-05-03.
Bang - Desperate Housewives - was created on 2006-11-05.
Guilty - Desperate Housewives - was created on 2004-11-28.
The Chase - Desperate Housewives - was created on 2010-02-28.
Impossible - Desperate Housewives - was created on 2005-02-20.