Skridger16,181 Locked 10 Nov 2017 11 Nov 2017
For this, you need to get one of your staff to level 7. (3 Stars) It's tough to do on career because your staff change every time you get to a new city. Best to do this in free mode. It took me around 10 duties before one of my cops made it to max.
To make it go faster, pick a unit and try to keep them active on as many calls as possible.