How do you know? For when I investigated it those two pieces are designed to move at times together and at other times independently. One can prove this by look at the latch of most modern doors and you will be able to move both together if one was to press the latch bolt but the other non bevelled bit can move independently without moving the latch The second bolt is there to prevent slipping a plastic card or whatever behind the latch bolt.
Now when Goncalo's security expert examines the front door he talks in Portuguese and we read the closed captions (from memory), but IMO Alexandre Simas has his words translated incorrectly. He talks of "screw" which I believe now to be "bolt", for there was no photograph showing a proud screw but we do have a latch with the latch bolt lock.
https://joana-morais.blogspot.com/2009/04/maddie-truth-of-lie-documentary.htm
"43.25 - Final Evidence
43.28 – With the help from one of the major experts from the Scientific Police, who worked for the Polícia Judiciária, Alexandre Simas, Gonçalo Amaral intends to prove, first, that it was impossible for the child to be abducted, starting by demonstrating that the indications prove that the apartment’s window and door were not forced.
43.47 - How does one open a door like this, without the key?
Alexandre Simas
Expert (Former Polícia Judiciária)
43.51 – This type of apartment door, normally there are only three possibilities: to extract the lock’s cannon, which didn’t happen, or it would have been reported; a false key, a copy or one that was used without permission; or using a malleable material, as long as it’s not locked, it’s introduced, and it makes the lock go back inside. But when it goes in, even if it did, it would hit this screw. If it hits the screw, no matter how much I force it, it doesn’t jump to open the lock for me."
I'm sure now where it says "screw" the right word should have been "bolt". When talking locks a bolt is not a threaded bolt with a head but a piece of metal that is movable.
But the interesting thing is the this proves beyond a doubt that the rim latch on 5A had been modified in such a way that "will NOT be able to move both together if one was to press the latch bolt".
In the latch on the front door of 5A the two pieces of metal moved independently at all times
To get the terminology correct I found this article.
https://www.gokeyless.com/blog/whats-the-difference-between-a-latch-and-deadbolt-and-which-is-better/where it says:
"LATCHES
Latch-based locking mechanisms are extremely common, with spring-loaded latches being the most prevalent type of device that is used within a typical lockset. Spring latches usually fall into one of two categories, as follows:
Latchbolts – These latches feature a spring-loaded bolt that is angled off at the top edge. As the door is closed, the angled side of the bolt will engage with the edge or lip of the strike plate (i.e., the hollowed-out plate fastened to the adjoining door frame), and the bolt itself will retract due to the pressure of contact with the strike plate. Once the bolt passes a certain point, it will fully extend and quickly lock into the strike plate due to the pressure being released from the spring, securing the door and holding it closed. Latches are designed to retract and disengage when someone turns the door handle to open the door.
Deadlatches – This device is a slight elaboration on the design of the basic latchbolt. Deadlatches feature what’s known as a guardbolt, which is a smaller cylindrical bolt positioned right beside the latchbolt. The guardbolt is designed to move in unison with the latchbolt up until the point where the latchbolt extends into the strike plate. At that point, the guardbolt remains in a depressed position against the strike plate, preventing the common burglary practice of “jimmying” or “shimming” the latchbolt. The way the guardbolt is positioned will not allow the latchbolt to be depressed by means of using a credit card or some other thin, flat tool."
So what was on the door at 5A was "deadlatch" with a deadbolt on top. The door could be left with just the deadlatch or for deadlatch and deadbolt to be in place.
