Since, "a little knowledge is a dangerous thing", I'll be reckless here 'bout the door...appreciate being filled in if/when the information becomes reliably available...
- Reading father deadbolted door shut earlier.
- Reading gf discovered a door (screen/storm?) propped open.
- Reading it was propped open with something akin to a brick/stepping stone/paver.
I am envisioning we're dealing with a two-door set-up here that has a screen/storm door outside of a solid door. One pic of the home appeared to have something like a screened porch on the back...dunno if that is what we are dealing with here....
Observations regarding the door/prop situation under these circumstances, assuming the father or gf aren't directly involved:
1) If the screen/storm door has a 'closer' or spring on it, or the door itself is noisy (as suggested above) and one wants to make a covert entrance & exit - esp. if one expects to be carrying something upon exit - one would prop this door open.
2) If access through the screen/storm door affords a better view into the rooms occuppied by the gf & Haleigh from the exterior one would prop this door open whilst one peered through the windows to afford a quick escape/exit if this began as a 'peeping Tom' incident, or, simply observing for the conditions inside the house to be 'right' for an abduction. If this is a screened porch situation that affords a 'peeping Tom' some cover, LE might find various forms of evidence present near in this porch area, esp. imediately near the window(s).
3) If the prop isn't native to the area of the door...its origin is very important...from a nearby home? If brought by the perp this certainly indicates some degree of advance knowledge/familiarity and planning. Origin of the prop will be telling.
4)
If this is a two-door set-up and there was no sign of forced entry...the perp has a key to the deadbolt lock, and if the propped door was indeed a screen or storm door that has the common inside-only operated lock set-up...well then...the perp had to prop this door open to ensure access to the deadbolt lock of the interior door at a (a) a time when the perp had legitimate access to open the screen/storm door (friend/neighbor/etc.) earlier that evening...or (b) at a time immediately after the door had been opened by the father or gf but not monitored all the way to closing. In either case, if the prop used is not native to the area and other objects that could've equally served as props were available...this tells us something about the circumstances of the prop being put into place.
5) If the door was screen vs. glass it would have been a simple matter of cutting the screen vs. propping the door open if this door was locked. A glass door would need to be propped open in some manner, or the latch would have to be interfered with in some manner...dealing with a glass door would be more problematic.
I'd like to know more about the door set-up, condition as-found, and the prop.