Go look yourself. It is one of the most widely agreed on facts of the case. Both the PGP and PIP agree on this.

Right, I'm claiming Mez committed suicide after locking herself in her room.
They tried the door as Raf attempted to break it down. Later the police broke it down compromising any prints.
I suggest you read the
PIP and PGP
From PGP. This is what Luca Altieri said. He was the one who broke down the door:
[excerpt]
Yes. Then later we also went out to realize how it was possible to get that window. It was not ... to me it seemed something quite unlikely to get that window, and because there was no access, that is not a circus acrobat would be able to climb the wall with a stone, break the glass and open it ... is my impression. And nothing, then after, inside the house, basically, we have seen that these two policemen post new arrivals were there to deliver two phones that had been found in a house, I did not understand what was this dynamic, however, were here with these two phones of English girl who lived one of the rooms of the house. We also saw that the door of the room of this girl was locked from the outside probably because there was the key behind the door. So we ... I myself have asked the two boys if it were normal, say, he used to close the door, that is, if it was normal that the door was locked. Raffaele, translating the response of Amanda, told me that he used to close the door even when she went to the bathroom to take a shower.
GM:
Meredith?
LA:
Yes. So there and then, so it is not born a concern with respect to the fact that the door was closed despite the theft even if it had been discovered these phones. After it is coming up with Paola Filomena after a while '. [excerpt ends]
---IOW he says it was apparent it was closed from the outside because "there was the key behind the door".
Marco Zaroli testified:
[excerpt]
I think it was one of the agents of the post that we said it, then and there was one thing ... since they had also found these phones, the thing that worried enough, however, since the response was that of Amanda Meredith was used, customary shut the room just to make a simple shower there tranquillizzammo enough.
GM:
Given the observation of ... in front of the comment of the Postal Police, one of the members of the police post, there was a locked door ..?
MZ:
No, at the express request of Luke, I asked him to Luke, "but ask him how ..."
GCM:
Here, excuse me a moment, that is what, if can be concluded. So, Luke, what does?
MZ:
If Meredith was normal ... if it was normal that Meredith's door was locked. The answer is "yes, it's normal, it also closes to go take a shower." So given that there was not at home and could have gone to the grocery store, we tranquillizzammo because it was plausible that the door was closed.
GCM:
The door was closed those who have discovered the first ?,
MZ:
I do not know, I've already ...
GM:
I have told the police ...
MZ:
Yes, we had already said, and had apparently already discovered.
GM:
In practice it is discovered by someone, the Postal Police takes note that there is a door, a closed chamber.
MZ:
Yes.
GM:
Everyone is wondering what could be there, Luke asks, Luke, if I understand, but Amanda asks why the door ..?
FM no Amanda:
{{{2}}}
GM:
O Amand asks ...
GCM:
Excuse me, then, yes, we hear. You're welcome.
MZ:
I remember that I asked Luke: "Luke, just ask the ..."
GCM:
She asked Luca?
MZ:
Yes. I said, "Listen ...", because at that time I remember I was talking Battistelli, "but feel a bit '' is the door" because we were worried of the situation.
GCM:
One moment, sorry. Yes.
MZ:
I asked and was told, again by Luke, that Amanda had said that it was normal that the door was cKIussT. '
GCM:
Here you are. Excuse me, perhaps to conclude on this, but ...
MZ:
Why, because the closed well to make a simple shower. [excerpt ends]
Filomena Romanelli testifies:
[excerpt]
She closed her door the key?
FR:
I did not have the key.
GM:
It was just her, or even other did not have the key?
FR:
I did not have the key, Laura and Meredith had the key, I do not remember if the room of Amanda, but I do not think so, I do not remember.
GM:
Senta but these rooms were left, during the day were left open or were closed, apart from her that she had no key so ...
FR:
Most were left open.
GM:
Were all open?
FR:
Yes.
GM:
Always open?
FR:
Yes. It seems to me that only once Laura Mezzetti going away for the weekend closed the room but because, he said, but this is not because I am reminded, however, I only know Laura Mazzetti.
GM:
And Meredith as he held the door, her room, the door ...
FR:
Open.
GM:
Always open. Feel the night ...
GCM:
When he says Excuse open means open not closed key?
FR:
Not locked.
GCM:
Or the door wide open?
FR:
Not locked.
GCM:
Closed ...
FR:
Not always closed, maybe sometimes pulled but not, say not closed, resting, but never unlocked, ajar, but never locked.[excerpt ends]
So, having acquainted myself with the facts from the webpages you suggested, it is clear when Amanda said Mez's door was always closed or locked, everybody else emphatically said this was not so.
Why did Amanda say she was supposedly frantically worried about Mez's locked door in her email home, before she was a suspect, yet Inspector Battistelli found her remarkably laid back about the door being closed?
[excerpt]
i then went into
the part of the house that meredith and i share and checked my room
for things missing, which there werent. then i knocked on merediths
room.
at first i thought she was alseep so i knocked gently, but when she
didnt respond i knocked louder and louder until i was really banging
on her door and shouting her name. no response. panicing, i ran out
onto our terrace to see if maybe i could see over the ledge into her
room from the window, but i couldnt see in. bad angle. [excerpt ends]
(Sorry, google translation.)