CAT/C/39/2 page 35 70 years (the latter involving homicides). Almost all the detainees were persons who had previously lived in difficult socio-economic conditions, with a low level of education and belonged to vulnerable social groups. 138. Nine out of 19 interviewees stated that they had been treated in a way the Committee members considered could fall within the definition of article 1 of the Convention. They claimed to have been subjected to torture by police agents at the beginning of their detention, in particular in order to obtain a confession. The mistreatment inflicted during this phase of detention was normally of a short duration, and did not result in haemorrhages or loss of consciousness, and consisted mainly in trauma caused by blunt instruments (essentially punches, kicks, slapping and occasionally, blows with objects). In the majority of the cases the results were contusions and haematomas that did not need medical treatment and healed by themselves. 139. One of those examined, who had been arrested the previous day, showed a haematoma on his right upper lip with a small horizontal cut on his inside lip, half a centimetre long. He stated that this was the result of a punch received from the police at the time of detention, an explanation that the medical expert considered totally compatible with the injury examined. 140. One detainee referred to open wounds incurred as a result of aggression by the police at the time of arrest and another referred to being subjected to the same type of injuries after being hit with the back of a spade/hoe by a prison warden. The physical examination clearly showed the existence of different sizes and shapes of scars, some almost oval, with pigmentation and hypertrophic, on the posterior-internal face of the forearm, the larger measuring about two and a half centimetres in diameter; and the other linear and oblique from top to bottom and from the outside to the inside, the biggest one measuring 12 centimetres, was located on his back. These areas of the body were the ones referred to as those subjected to aggressions. 141. In one case, reference was made to the practice of electric shocks, administered twice, in connection with a detention which had occurred in the second half of the 1980s, but no physical trace of such practice were found. 142. In another case, the practice of mistreatment by twisting the thumb repeatedly was alleged. The medical examination showed rigidity of the thumb. 143. In two cases the medical doctor found surface scars on the detainees’ backs compatible with aggression with blunt instruments used in arrests by the police. Scars were linear, sometimes double and parallel, some oblique from top to bottom and from the outside to the inside, others almost horizontal, the biggest one measuring 11 centimetres. 144. In the case of a young detainee, the medical doctor found a scar on the left buttock measuring 3 centimetres which was compatible with the report made that he was hit by rubber bullet shot by a prison warden during a rebellion in the juvenile detention centre where he was detained. 145. The medical expert observed one case where the detainee alleged that he was the victim of repeated torture. This took place during a previous detention in the 1980s. He remembered having been taken to a room, which could have been an office, where he was placed in a position called pau de arara, while police agents hit him on his back and head. During the torture he was