DALLAS -- To say the last 21 months have been a rollercoaster for Messina Madson is an understatement.

“I don't think I've stopped moving since that moment,” she says.

She was tapped to be Susan Hawk's second in command in April 2015 after Hawk fired her predecessor.

Madson's been the district attorney -- not in title -- but in reality for much of the last 21 months.

Friday was her last day on the job in the office that she’s worked for her entire professional life since graduating from SMU Law School 12 years ago.

“These are not circumstances anybody would choose," she said. "However, in hindsight, I'm a better person because I've been tested in this way and given this opportunity."

Madson, 38, is proud of changes she's overseen: The civil rights unit that responds to each officer-involved shooting, creation of the largest DA-run diversion program that gives offenders a second chance and the DA in the schools program, to name a few.

“I think this office has become a true thought leader in criminal justice reform,” Madson said.

There have been low points.

In the summer of 2015, Hawk secretly left to seek treatment for mental illness after becoming suicidal. The questions about Hawk’s whereabouts inevitably came.

“I knew she was struggling and I had to be prepared to make sure this office ran smoothly no matter what,” Madson said.

Hawk returned to work in the fall of 2015. Madson was by Hawk’s side when she spoke to the media that day.

“I was proud of her for stepping away and getting the help she needed,” she said. "She gave her entire life to the criminal justice system. It didn’t have an easy solution. I think if there had an easy solution then it would have been fixed a long time ago. I think I’m more aware of how people who are dealing with mental illness struggle. I’m more sympathetic and compassionate to the people around them.”

She'd hoped Hawk could soldier on.

So it was hard to watch as Hawk struggled mightily with mental illness, sought treatment again for mental illness and then stepped down in September.

“It was a very difficult situation and I always wanted her to be better," she said. "I still want her to be better. I care about her. I knew it wasn’t an easy decision for her to make, so once she made it, I immediately mobilize in what needs to be done mode.”

The consummate organizer, Madson had legal analysis done to determine what needed to be done so that the wheels of the criminal justice system continued to move.

She and Hawk remained in contact. She said she called Hawk to let her know that she would be stepping down. She couldn’t comment on Hawk’s current condition.

Madson said she had hoped to get the job that Gov. Greg Abbott ultimately gave to former district court Judge Faith Johnson.

“I didn’t feel entitled to it,” she said. "I really believed that this administrative staff is the best I could have ever worked with. We had worked on amazing things that I was very proud of.”

Madson says there was no discussion with Johnson about staying on.

“She is going to have an opportunity to do great things and so I think that this office is full of men and women who are the best in the nation at being trial attorneys and she's lucky to lead them,” Madson said.

I asked what’s her advice to the people still working there?

“Remember that you were coming into contact with people who are broken," she said. "Something very bad has happened to them."

So what will she be doing come Monday? She told me she'll be making preparations to start a firm with a friend from the DA’s office.

Madson says she'll miss the camaraderie of the office, that sense of working in the trenches and feeling you get when you win justice for a victim.

“We all live for the moment when you have a jury come in and you have a victim whose broken and worried and they get the verdict they’ve been hoping for and then you hear them collapse a little behind you with relief,” she said. "And you know your job’s done and you feel that moment of victory, that moment of success, that moment of belief in the system. Every prosecutor lives for that.”

A litigator at heart, Madson said she's itching to return to the courtroom.

“My home is in the courtroom,” she said.

Not surprisingly, there will be no big goodbye parties for the admittedly reserved, soft-spoken Madson. She said she's just happy to get the time “to go breathe.”

“I’ll take a little bit of time but I am a structured person,” she said. “I am full of lists and to-dos and organize around me, including myself so it won’t be very long.”

On Friday, she had her office all packed and ready for her successor. She showed us the neatly organized, color-coded desk drawer.

“I want to be able to organize the world,” she joked. “I want to color code. I want to tab it. I want to walk away with an outline of what needs to be done.”

She’s leaving everything in place in the drawer for her predecessor. She says she can’t bear to dismantle it.

“This is what the next first assistant will walk into,” she said. “I just want them to be ready for whatever comes.”