. ▁Re ci bió ▁forma ción ▁especial , ▁se ▁resist ió ▁a ▁descri bir la , ▁pero ▁nad ie ▁qu iso ▁preg unt ar le ▁en ▁qu é ▁consist ía ▁esa ▁forma ción . ¿ El ▁polic ía ▁que ▁prepar ó ▁las ▁bomb as ? ▁Un ▁' s op lo ' ▁pol icial ▁ad virti ó ▁a ▁Kal aj i ▁de ▁que ▁se ▁estaba ▁investig ando ▁su ▁papel ▁en ▁los ▁at ent ados ▁del ▁ 1 1 - ML a ▁familia ▁Kal aj i ▁y ▁el ▁ 1 1 - M ▁Kal aj i ▁was ▁not ▁one ▁of ▁those ▁accused ▁in ▁connection ▁with ▁the ▁bomb ings , ▁though ▁the ▁police ▁proposed ▁to ▁take ▁him ▁into ▁cust ody . ▁ ▁The ▁th ir teenth ▁bomb ▁Cl ues ▁from ▁the ▁th ir teenth ▁bomb ▁allowed ▁the ▁police ▁to ▁arrest ▁the ▁first ▁alleg ed ▁perpet rat ors , ▁three ▁Mor occ ans ▁( J am al ▁Z oug am , ▁Moh amed ▁Cha ou i ▁and ▁Moh amed ▁Bek k ali and ) ▁and ▁two ▁Indian ▁citizens , ▁on ▁Saturday , ▁ 1 3 ▁March . ▁The ▁bomb ▁has ▁been ▁called ▁" the ▁bomb ▁that ▁dis mount ed ▁the ▁P P ▁version ▁of ▁E TA ", ▁and ▁was ▁known ▁to ▁Spanish ▁sources ▁as ▁" M och ila ▁de ▁Valle cas ", ▁" Back pack ▁from ▁Valle cas ", ▁because ▁its ▁discovery ▁was ▁announced ▁in ▁the ▁Valle cas ▁Police ▁Station ▁on ▁the ▁morning ▁of ▁ 1 2 ▁March . ▁The ▁th ir teenth ▁bomb ' s ▁valid