Dan, do you think it's possible the round handle on the outside of the door could be an actual functional handle rather than one just for pulling the door shut? In other words, that the handle is linked to the closing/locking mechanism of the door, and works in the same way as the lever handle but is a different style. So you could turn that handle to open the door and operate the latch (if it weren't jammed) and turn it the other way in order to lock the door (equivalent to lifting the door handle to lock it on the other side).
It is certainly possible that the exterior door handle could be (or could have been) operable. It isn't any sort of a standard configuration, and would require a lockset specifically designed for the purpose. (This is as opposed to locksets which are generally designed to accommodate a wide range of configurations, and require only adjustments within the lock body mechanism to implement or disable different features.) I haven't run across one such myself, but I don't claim to have encountered every sort of lockset, just a great deal of them.
The fact that the interior handle is a lever handle, and the exterior a knob isn't relevant. Both function exactly the same as far as a lock mechanism is concerned. The difference stops at the surface of the door. Both, when operable, rotate a shaft extending into the body of the lock.
My point, with which Dan_O evidently concurs, is that a lockset with a key cylinder which operates
both the spring latch
and deadbolt is a very common configuration. What
isn't common is a door hardware design on a residential entry door which requires an occupant to be present for the configuration to function as intended.
The subject is somewhat moot, though, from my perspective. Even if the exterior door handle had been operable at one time and then failed, the fact remains that the impression I had initially gotten of a spring latch which wasn't working quite right and didn't secure the door
properly is still quite different from one of a latch which is not working
at all and has been intentionally disabled. The former would
feel like it was operating properly, and then fail, perhaps at some later time. This is the scenario which has been so vigorously propounded by those suggesting that Guede did not
notice that the door wasn't functioning properly, and up until I saw those photos I had accepted that as a possibility. The latter would feel
wrong. It would be quite apparent to even a casual user.
I agree that there are no rollers on the door, and as I said in the other post, I think those grooves are for additional locks which - in the case of two of the doors on our house, anyway - are operated when you lift the handle to lock the door. But if that were the case with this door, there would need to be some way to activate those additional locks on the other side of the door too (or you wouldn't be able to lock it with the key) which is why I'm wondering about the handle.
Hope that's clear, it's a little difficult to describe!
I still haven't seen the grooves that you are referring to. The link you included in your earlier response to me did not seem to go to a photograph which showed what you intended me to see.
It may be that you are discussing "vertical deadbolts", or "flush bolts" (two different but similar things). But at this point I'm just guessing. This could take the discussion rather far afield, and without seeing some more specific pictures within the context of the Knox apt. door I can't provide any enlightenment.