Carson is a very well-known lawyer in River Heights. He tends to be out of town working on cases of his own, but he is still very supportive - and protective - of his daughter. In fact, several of Nancy's cases have come from Carson or his various friends and colleagues.
His beloved wife, Kate Austin, was a journalist and a spy. When their daughter Nancy was around ten years old, Kate was contacted by her friend Moira in Scotland and asked to come to Glasgow to help defeat the terrorist organization Revenant. Carson was terrified that something would happen to her and absolutely refused to let her go, reminding her that she promised to retire from spy work for the sake of Nancy. They had a big fight, but Kate left anyway.
Carson's fears proved to be justified when Kate was killed in a suspicious car crash. Her death affected him deeply and he was very reluctant to talk about her ever since. Newly widowed, he hired Hannah Gruen to be their housekeeper and Nancy's mother figure, and tried his best to restrain his protective tendencies and allow Nancy freedom to go on cases.
Secret of the Scarlet Hand
At the start of the game, Nancy wrote to him while he was in Ouagadougou (capital of Burkina Faso). From there, he was going to move to Nairobi (capital of Kenya). Franklin mentions he got a postcard from Carson in Ouagadougou, and Nancy mentions he is trying to go on a safari while in Kenya.
The day the mystery ends, Carson calls Nancy, as stated in her letter.
The Haunted Carousel
Carson offers Nancy's services to his friend Paula Santos.
Danger on Deception Island
According to Hannah's e-mails, Carson was supposed to be in court, but the courthouse flooded and - having nothing to do - stayed home. Soon, he is driving Hannah crazy. He tried to make breakfast, but made a mess in the kitchen; he then ruined a bookshelf that he had to fix. Hannah finally got so fed up with him, she sent him out on a jog.
The Secret of the Old Clock
Danger by Design
Carson once again offers Nancy's services to his friend Amy Grunhild. Before Nancy goes to Paris, he makes her promise she won't go out at night.
The Creature of Kapu Cave
Carson sees a story about Dr. Quigley Kim, and Nancy agrees to fly out there to help her.
Legend of the Crystal Skull
Carson and Mr. Marvin agree to pay for Nancy and Bess's vacation to New Orleans.
Lights, Camera, Action!
Ransom of the Seven Ships
Nancy is a day late to Dread Isle because she attended a father-daughter banquet with Carson.
Alibi in Ashes
Carson is in Australia when Nancy is framed and arrested for arson. Carson is outraged, and promises that he'll drop everything to return home and help her. Nancy convinces him that she can handle it, and if she needs his help, she can simply call him. Even so, he swears to be home immediately if things get any worse.
The Silent Spy
Carson is horrified when he discovers that Nancy has snuck off to Scotland to deal with the very same organization that killed her mother. He demands that she return home, and when she refuses, he heads to Scotland himself to drag her back. His fears only increase when his passport is tampered with by Revenant.
Almost driven out of his mind with worry, he acts very hostile towards Nancy for a majority of the game. He catches Ned breaking into the house (under Nancy's orders), and while yelling at Nancy over the phone, Ned points out his attitude. Carson allows Nancy to continue her investigation with extreme reluctance, mostly because he has no choice.
When Nancy successfully returns home, she and Carson finally talk about their memories of Kate and promise to talk more with each other in general.