A direct statement by a defendant is treated as pretty much prima facie evidence (cf Ruth Ellis testifying she 'wanted to kill' the victim= summary hangman's noose).
Only if that direct statement is judged to be reliable and credible. Not if there is a reasonable suspicion that the statement was, for example, the result of unlawful coercion.
Perhaps I might direct you once again to the interesting documentary shown on Discovery Channel: "Secrets of Interrogation". It contains a textbook example of improper police coercion in the interrogation of a 20-year-old man of average intelligence.
Fortunately for anyone who has a serious and sincere interest in this subject, the interrogation was videotaped. I very strongly recommend that you watch it - you might well get educated and enlightened. The relevant part of the programme starts at around 26:00.
http://www.dailymotion.com/video/xr...of-interrogation-hdtv-xvid-diverge_shortfilms
The man is repeatedly and aggressively told that the police "know" he was present at a murder, and that they have evidence to prove that. The police then instruct the man to tell them the "truth" - i.e. that he participated in the murder in some way - or the consequences for him will me hugely more serious. The police instruct the man that admitting to them that he was present at the murder - and at the same time giving them information on the person(s) who actually killed the victim - will be massively to his benefit; if he does not do so, then the police will seek for him to be charged with the murder itself. The man is being given a Sophie's Choice.
Eventually, the man takes what seems to him to be the option which is the "least detrimental" to him. He states "OK, I was there", and makes exactly the "confession" that the police are ordering him to give. He includes details which do no more than mirror the things that the police have already told him.
In so many respects, this scenario is extraordinarily similar to the conditions under which Knox was interrogated on 5th/6th November 2007. Knox too was told that the police "knew" she was present at the scene of the murder. Knox too was told that if she didn't "remember the truth", then she would face far more serious and damaging consequences: telling the police the "truth" that she had met with and facilitated Kercher's killer would be far more beneficial to her than saying nothing and getting charged with (and convicted of) the murder itself.
In the case of the man in the documentary, however, incontrovertible evidence soon materialised to show conclusively that he was actually thousands of miles away in Brazil*. His whole "confession" could be proven beyond all doubt to have been a false confession, which had been improperly coerced from him in the interrogation.
I wonder how this cast-iron false confession sits with the (flawed) belief that "A direct statement by a defendant is treated as pretty much
prima facie evidence".......?
There are none so blind as those who will not see.
* Fortunately, the US police department investigating this case, despite their huge and obvious (and documented on video) misconduct and failings in the interrogation of this man, were apparently honest and diligent enough to set aside tunnel vision and confirmation bias in their quest to verify the man's confession. Unlike some other regional police forces in another country that might come to mind.........