Have a look on the test demo as I have created a process on there that may work.
On the process it looks to see if the tech os blank and if it is it will always put the ticket to open, so can never be closed until tech entered. In here you can also assign to a tech but can not choose the one who opened it so you could have them all assigned to a manager or something
Look in processes > action rules for "close ticket without tech"
Hope it helps