The consultants and forensic scientists have asserted that from the point of view of forensic science, it cannot be ruled out that the author of the injuries could have been a single attacker, because the bruises and the wounds from a pointed and cutting weapon are not in themselves incompatible with the action of a single person. With regard to this, it is nevertheless observed that the contribution of each discipline is specifically in the domain of the specific competence of that discipline, and in fact the consultants and forensic experts concentrated their attention on the aspects specifically belonging to forensic science: time of death, cause of death, elements indicating sexual violence, the injuries present on the body of the victim, and the causes and descriptions of these. The answer given above concerning the possibility of their being inflicted by the action of a single person or by more than one was given in relation to these specific duties and questions, which belong precisely to the domain of forensic science, and the meaning of this answer was thus that there are no scientific elements arising directly from forensic science which could rule out the injuries having been caused by the action of a single person. But, to actually answer this question, of whether the criminal action which determined Meredith's death was the action of one person alone or several people acting together, it is necessary to take into account, not only the contributions of forensic science, but also other elements which have emerged and which are relevant to this point, and to evaluate the situation in a way which takes the comprehensive picture into account.
One first such additional element is what has been said of Meredith's personality and her physical condition; one must take into account that, according to what has already been noted, Meredith, when the attack began, [395] was awake and dressed and not lying on the bed; additional elements are given by the place in which the violent action appears to have taken place, of which the file of photographic documents make it possible to determine, as they represent Meredith's room, with the various pieces of clothing and objects present there.
In fact, putting together the elements mentioned above - including, of course, the forensic observations - it is considered that the injuries and the violence were the result of an action of several people.
A first indication to be taken into account is Meredith's physical build: the photographs of her body and the data of her approximate height and weight reveal a physique with "normotrophic muscular mass and normally distributed subcutaneous fat" (cf. declarations Lalli p. 3), a slim physique which would have permitted Meredith to move with agility. To this must be added the declarations of the parents and the sister of Meredith. Her mother, Arline Carol Mary Kercher, recalled that Meredith had practised football and karate (p. 7 hearing 6 June 2009), and her sister, Stephanie Arline Lara, stated that Meredith also did boxing, if only the once, and that "physically she was very strong" (p. 20, hearing 6 June 2009). Also her father, John Leslie Kercher, declared that his daughter was quite strong and had taken a course in karate (p. 23 hearing 6 June 2009).
It has also been noted that Meredith was not in bed and undressed when the "advances" and the attempts to subject her will commenced. Being still dressed and awake, and since it must be excluded because of what has been said above that the violent action could have taken place with Meredith lying on the bed, it is considered that she, who was sober and fully conscious since no traces indicating either the use of drugs or the abuse of alcohol were found, would have opposed a firm resistance, as she could claim a strong physique, experienced in self-defence by the lessons in karate that she had taken. The signs of this resistance, however, consist in a scream, the scream heard by Nara Capezzali at around 23:30 and by Maria Ilaria Dramis when, having gone to bed at 22:00 pm, she awoke at a later time which she was not able to quantify; they consist also in some tiny defensive wounds: one on the palm of her right hand of a length of .6cm showing a tiny amount of blood; another on the ulnar surface of the first phalange of the second finger of the left hand, also of length .6cm; another on the fingertip of the first finger with a superficial wound of .3cm, and another tiny wound corresponding to the fourth radius.
Compared with these almost nonexistent defensive wounds (cf. report of Dr Lalli, pp. 33, 34, 35 with the relevant photos), there is an injured area which is impressive by the number, distribution and diversity, specifically of the injuries (bruises and wounds) on the face and neck of Meredith.
This disproportion is all the more serious and inexplicable if one considers Meredith's physical and personality characteristics recalled above. It seems inevitable that it must be considered that the criminal action was carried out by several people acting together against Meredith, who, strongly limited in her movements, could not defend herself in any way nor shield herself with her hands in order to avoid a vital part of her body (the neck) being repeatedly struck.
Furthermore, it is impossible to imagine in what way a single person could have removed the clothes that Meredith was wearing (shoes, pants and underwear), and using the violence revealed by the vaginal swab, could have caused the resulting bruises and wounds recalled above, as well as removing her sweatshirt, pulling up her shirt, forcing the bra hooks before tearing and cutting the bra. In order to maintain such a hypothesis (action performed by a single attacker), Professor Introna suggested that Meredith was undressing, and thus when her attacker arrived, she had already removed her own shoes, pants and underwear; the attacker would have come up from behind, thus taking her by surprise. But this reconstruction appears unrealistic, as we have seen. It must also be noted that the representation of Meredith's room with the distribution of the various furnishings and the direction of opening of the door towards the interior of the room (see in particular photos 80, 89, 94) makes it rather improbable that someone entering into that room could have surprised Meredith from behind, especially as in addition, and there seems no reason for this as already noted, [397] she would have had to be (but one cannot see where in the room her attacker would have been able to surprise her from behind) naked from the hips down.
The breaking of the bra alone, from which a small piece of material with hooks (photos 140, 119, 118 and 117) was cut off and thrown to the floor, by an act which was necessarily conducted from behind Meredith (one cannot see in what other way the bra could have been thus forced), requires the following observation: such an action would occupy both hands of the attacker, and thus Meredith would have had her hands free, and in that situation she could have attempted some action in self defence (for example trying to run out of the room and attempt to flee, in other words reacting towards her attacker by getting away from him), whereas in fact there is no trace of such a thing, and it seems inexplicable unless it is admitted that several attackers were present, with a distribution of tasks and roles: either holding Meredith and preventing her from any significant defensive reaction, or actually performing the violent actions (and here one must recall that a biological trace of Rudy was found on one of the cuffs of Meredith's sweatshirt, which appears to be the sign of having gripped Meredith in order to prevent any reaction, any defence). Also the diverse morphology of the injuries and their number and distribution lead one to consider that those participating in this criminal action were more than one. Many injuries appear to have been caused by an activity of restraining; others were inflicted by a pointed and cutting weapon, and are greatly diverse in dimension and harmfulness; furthermore, even when directed at the same part of the body they sometimes attained the victim from the right and sometimes from the left. In fact, in order to maintain the hypothesis of a single attacker it would be necessary to hypothesise that the same person continually modified his own harmful conduct, first exercising a strong manual pressure on the victim, producing bruises, then deciding to seize the knife, thus changing the very nature of the attack (now armed rather than with the hands) and then striking first on the right (4cm wound) and then on the left (8cm deep wound). In the first case, a single blow was apparently halted by the jawbone (4cm deep wound), and instead in the second case, the knife was held inside the victim's neck, after the same knife having been used to run over the surface of the same part of the neck, just a few centimetres below the zone on which the more serious and deeper wound was inflicted. Furthermore, in spite of all these changes in the action of the attacker, Meredith would have remained in the same position, continuing to offer the same part of her body (the neck) to the attacker who would in the meantime have picked up a knife. Yet after the first wound, the normal and instantaneous reaction would have been to protect the wounded part (the neck, precisely, which would have moved away from the possibility of another blow) even running the risk of receiving the blow on another part of the body. Conversely, considering the neck wounds sustained, it must be believed that Meredith remained in the same position, in a standing position, while continuously exposing her neck to the action of the person striking her now on the right and now on the left. Such a situation seems inexplicable if one does not accept the presence of more than one attacker who, holding the girl, strongly restrained her movements and struck her on the right and on the left because of the position of each of the attackers with respect to her, by which it was easier to strike her from that side. One of these attackers was Rudy and the others were those who allowed Rudy to enter the house and who were with him in the house and who, in order to lead the investigations astray, then organised the staging of the broken window and the mess in Romanelli's room: Amanda Knox and Raffaele Sollecito, according to all that has already been shown.