No one is disputing that those who signed that open letter are experts in their fields, but so what? The letter has not been submitted as evidence and none of those who signed it have testified. The letter means nothing.
Dr. Hampikian seems to be quite keen on helping the defense, why hasn't he testified for them? Here we have a DNA expert willing to testify and what does the defense come up with? A guy that beat a baby to death with a shovel. There much more going on behind the scenes here even though those advocating innocence claims that if there was anything important happening we would know about it.
Is it seriously necessary to explain once again how this appeal trial is proceeding? Oh well, here we go again....
Prior to the start of proceedings in the appeal trial, the defence and prosecution can both produce submissions to the court, in which they can list areas in which they believe the first trial erred or was deficient. In these submissions, they can also request that the appeal court allows certain additional evidence or witness testimony, along with their reasoning why they feel the court should allow the new evidence/testimony.
Are you with me so far?
So, the first substantial ruling that the lead judge in the first appeal trial (here, Hellmann) has to make is about which (if any) of the prosecution or defence requests for additional evidence/testimony he will allow. The evidence/testimony that he decides to allow is then introduced into the court, and is added to the body of evidence/testimony carried over from the first trial.
Still with me?
The argument phase of the appeal trial can then begin, based on the combination of the evidence/testimony carried across from the first trial and the additional evidence/testimony introduced in the appeal trial.
Does it make sense?
So...... where are we right now? Well, the defence teams made a number of requests for additional evidence/testimony in their submissions to the appeal court. Judge Hellmann has ruled (last December) that he would immediately allow a full independent review of all the DNA evidence from the first trial. At the same time (last December) he added that he agreed to recall Curatolo to the stand. And also at the same time, he stated that he reserved the right to allow other evidence/testimony from the defence requests on an ongoing basis - mainly subject to the receipt and discussion of the new independent DNA report.
Sure enough, since the DNA report was delayed in its submission (thanks to the obstruction of world-renowned forensic examiner Stefanoni), Hellmann decided to use the time in allowing the inmate witnesses to be heard. Then, following their testimony yesterday, he also agreed to allow Guede and Benedetti (Guede's Skype friend) to testify. All additional grants by Hellmann on an ongoing basis. The defence didn't "come up with a guy that beat a baby to death with a shovel", as you so prosaically and pejoratively put it. The request to hear the inmates was just one of many requests made by the defence in its submissions several months ago - it just happens to have been allowed (correctly) by Hellmann while he is waiting for the DNA report to be submitted to his court.
And once the DNA report is submitted and discussed (by the end of July), Hellmann again has given himself the room to allow yet more new evidence or testimony. My guess is that he might allow the pillowcase stain to be tested, and that he will likely allow the alleged new computer evidence (and associated testimony) to be introduced.
Regarding DNA, I think you may well find that the report prepared by Conti and Vecchiotti addresses (and agrees with) most of the concerns raised by Dr Hampikian. If that's the case, then the defence need not require him (or any other expert in the field) to testify as to just how rotten the DNA evidence was in this case.