MM is described as Leandro Silva's friend.
Yes, but I find it confusing.
In the summary of the case that you'd posted (and I'd also remembered this from press reports):
The prosecution claimed that Joana was killed because she saw her mother and João Cipriano, her mother's brother, having incestuous sex, in accordance with the testimony of the stepfather of Leandro Silva, the common-law husband of Leonor Cipriano. [/u]
However...
In the Supreme Court doc, the "stepfather" is called MM.
A testemunha MM, padrasto do II... he would seem to be the "stepfather" to whom João had confessed at the PJ HQ.
But then, the same document refers to the stepfather as DD1:
11. 3. 5. Depoimento indirecto
Duas testemunhas - o companheiro da recorrente, II, e o padrasto deste, DD1
but I can't find a witness statement from any DD1.
Elsewhere in the same SC document, MM is described as a "friend".
ag) e, como sabiam que o companheiro da arguida BB - II - e o amigo deste, MM. And he's the guy that Leandro had gone out for a drink with that evening and who helped in the search.
In the same ruling, MM apparently lived with the family:
A testemunha MM, que à data viva em casa da BB e do II
According to a document related to the torture trial, the name of the man living with the family is Carlos Alberto Pinto da Silva.
In an article by Algarve Resident, Carlos Alberto is Leandro's half-brother:
Assistant Prosecutor, José Carlos Pinheiro, has arranged for several key prosecution witnesses to be summoned to court. These include António Leandro (stepfather of Joana), his mother Lurdes David, half-brother Carlos Alberto, Anabela Cipriano and Anatólio Duarte (sister and brother-in-law of Leonor and João Cipriano) and Nelson Cipriano, the defendants’ brother.
According to an article in CdaM, Carlos Pinto (a mechanic) was made arguido on 22 Sept on suspicion of having assisted in concealing the body:
Dia 22 - O mecânico Carlos Pinto é constituído arguido, por suspeitas de participação na ocultação do cadáver.
From various documents, he seems to be scrapyard man.
And unidentified blood was found on MM's trainers found between two sofas:
num par de ténis de MM Silva que se encontrava entre os sofás, numa esfregona (haste) e respectivo balde
(whether there was actually any blood or not isn't clear).