No...once you've been made a formal suspect or/and arrested.
Is it different for witnesses in the US Mary?
In this post, you appear to separate "being made a formal suspect" and "being arrested" - implying that the two are not only different, but by logical extension one can precede the other in time (or CAN SOMETIMES be simultaneous). Yet in a reply to me just a few posts earlier, you say:
"Which translates to making him a suspect which in turn translates to arresting him. The Italian equivalent of 'under caution' is 'formal suspect'."
What you write there in the first sentence implies that the very act of making Lumumba a suspect is analogous to arresting him (i.e. explicitly interlinking the statuses of "suspect" and "arrested person", and painting them as necessarily simultaneous events).
Which of the two positions better reflects your beliefs of how the Italian criminal justice system works?
But then the situation gets even more confusing. Your second sentence above explicitly equates the Italian "formal suspect" with the UK "under caution". I would agree with this comparison. But I therefore believe that in neither case is a suspect automatically deemed arrest-worthy. Any arrest would be the following step in the process.
From your knowledge of Italian law, can someone be officially denoted a "formal suspect" without being arrested? My current belief is that this can indeed happen. If "formal suspect" is the equivalent of "under caution" as you yourself allege, then presumably a formal suspect can be asked to attend a police station voluntarily - with attorney if required - but not kept in custody against his/her will. And it's what I argue should have happened to Lumumba - unless and until he either became non-compliant in any way or he incriminated himself in interview.
Of course, I'm also absolutely not arguing that someone COULD go from being of no status whatsoever in an inquiry to being arrested immediately. But I'd argue that the very few ways in which a person could be elevated in such a quick manner would be, for example, if their blood or semen DNA had been found on the murder victim (or murder weapon), or if there was very reliable and corroborated eyewitness testimony, or if explicit documentary evidence (e.g. emails, other recorded communications) clearly and directly implicating the person was discovered. I would argue that in nearly every other instance, the person in question should at least be given the chance to explain themselves voluntarily (as a "formal suspect" in Italian parlance, or "in interview under caution" in the UK parlance) before they are formally placed under arrest.