assuming you still didnt do it yet
You can ask Sammy and Lin Lin for Don's men scheledule,but first you need to talk to Fawn first,after waiting for one day,ask her again,then you can ask Arlene (The police officer),then talk to both Lin Lin (Cost money) and Sammy (You can ask Lin Lin to knock out the Don's Guard,although its optional),then you can ask some Hobo for help (you need to convince him) to cause some ruckus (Cost 1000 credits),then wait for one day,back to the hobo again,you will notice he isnt there,go to gentlemen club,you will see the hobo,confront him and you get 500 credits back,back to hobo refugee,give the remaining 500 credits,wait for one day and go to Police Station,you get a scene,then you can start to rescue Cassie