On Friday, Mr Mogensen will walk out of the Stanley St building for the last time, bound for Auckland and job hunting.
The 35-year-old began with the Ministry of Justice on "January 26, 2005, at 9am", where his office was the old Queenstown District Court - now the home to Guilty Bar.
"It was, in its own way, an absolutely fantastic beginning.
"It was like stepping back in time."
The former courthouse, which dates back to 1876, featured small rooms, no heating and the occasional rodent.
"It was a brutal experience," Mr Mogensen said.
He was also there when the former courthouse closed and the Ministry of Justice took up residence in the Stanley St building, part of Ngai Tahu's Post Office Precinct development, in September 2006, with the official opening held the following month.
The new offices featured plenty of space, housing "substantially more" staff, heating and air conditioning.
"I look back on it now - where we've come from to where we are now and it's just fantastic.
"It's a great team and a fantastic facility."
Before beginning his tenure with the Ministry of Justice, Mr Mogensen had a "random" work history, which saw him start as a manager for Allied Security, under Damien Black, then study for a bachelor of business studies degree.
After graduating, Mr Mogensen tried his hand at personal training for three years, before becoming a sales rep for Coca-Cola, based in Cromwell.
The company was restructuring, so Mr Mogensen decided to apply for the job as the Queenstown District Court manager - "I don't know [why]".
The job was "hard to quantify" but covered all aspects of the day-to-day running of the court, from financial delegation to staff training, staff leadership and "stakeholder relations".
The highlight of his job had been the team he worked with every day and the "good people" he had met over the years.
"It sounds a bit cliche, but it's true.
"It's going to be the people - the relationships I've built and the people I've met - that I'll miss."
However, the most memorable day for Mr Mogensen was the swearing in of Judge Kevin Phillips at the old Queenstown District Court in February 2006.
"He was ... I believe, the first and last judge to be sworn in in the old Queenstown Court.
"They have to take an oath and I don't believe we've had any other judge actually sworn in before the Chief District Court Judge Johnston in the old Queenstown Court.
"It was very special - it was the fact that we were moving into the new building, he is a local and he is an absolutely wonderful man."
On the regrets side, there was only one.
"I missed my last Criminal List day.
"I was in Auckland.
"There are always things that you could have done differently, but if you did them differently, you wouldn't be the person you are.
"I don't regret anything [else]."
The avid golfer, sports enthusiast and race-car owner said he would begin a road trip this weekend with his two dogs in the back seat, bound for Auckland, where his wife Rachel, a corporate lawyer, is now based.
