166. According to the case file, in the framework of implementation of the provisional measures granted by the Inter-American Court in March 2015, the General Prosecution Service of the State of Chihuahua requested technical assistance from the expert Pedro E. Díaz Romero to propose strategies for investigating the facts of the case, for which an international team of experts was set up.209 167. On March 31, 2015, the team of experts, made up of Pedro Díaz, Lucía Luna, Carlos Rodríguez, and Guillermo Bedoya, submitted its final report,210 in which it concluded that the evidence collected by the PGR established that members of the 35th Infantry Battalion had taken part in the disappearance of the alleged victims and that said evidence supported a request to the judiciary to arrest Colonel Elfego José Lujan Ruiz. As described before, this request was denied by the federal judge and the court of second instance.211 That report also concludes that it may be inferred from the evidence that staff from the District Attorney's Office of the State of Chihuahua in the municipality of Buenaventura, Federal Police of the PGR, and some senior army officers were later instrumental in ensuring the removal and concealment of the victims and in continuing to refuse to provide information to their next of kin and legal counsel on their whereabouts.212 168. The report made a series of recommendations of the steps required to strengthen lines of investigation to prosecute the perpetrators as well as to improve strategies for searching for the victims. Among other matters, the report raised the necessity of exploring ties between the murders of three federal police officers and the facts of the case and of strengthening, in keeping with the decision of the court that denied the request for an arrest warrant against Elfego Lujan, evidence of the participation of army personnel in this operation.213 169. As reflected in the case file, four lines of investigation are being pursued: (a) participation of personnel from the Secretariat of National Defense; (b) participation of organized crime groups operating in the area where the incidents occurred; (c) participation of Federal Police officers; and (d) evidence leading to the whereabouts of the Alvarados.214 170. In the course of preliminary inquiry AP/PGR/SDHPDSC/UEBPD/M5/50/2014, 126 witness statements and 196 pieces of documentary evidence have been collected, 10 inspections conducted, and 27 expert reports produced.215 7. National Human Rights Commission (CNDH) - Recommendation 43/11 171. On January 4, 2010, Jaime Alvarado Herrera, Alvarado’s brother, lodged a complaint with the National Human Rights Commission headquartered in Ciudad Juárez, Chihuahua, against SEDENA, requesting an investigation of the incidents that took place on December 29, 2009, to the detriment of Nitza 209 Annex I. Case file. Volume XXV, part 3. Request for collaboration from the PGR to the PGR of Chihuahua, March 19, 2015, page 112 of the pdf. (Annex to the petitioners’ observations on the merits received on June 9, 2015). 210Annex XX. Final report of the International Team of Experts (EIP), March 31, 2015, page 9. (Annex to the petitioners’ observations on the merits received on June 9, 2015). 211Annex XX. Final report of the International Team of Experts (EIP), March 31, 2015, page 9. (Annex to the petitioners’ observations on the merits received on June 9, 2015). 212Annex XX. Final report of the International Team of Experts (EIP), March 31, 2015, page 9. (Annex to the petitioners’ observations on the merits received on June 9, 2015). 213Annex XX. Final report of the International Team of Experts (EIP), March 31, 2015, page 64. (Annex to the petitioners’ observations on the merits received on June 9, 2015). 214 Annex I. Case file. Volume XXIV, part 2, Figures concerning the measures taken in response to the disappearance of Nitza Paola Alvarado Espinoza, José Ángel Alvarado Herrera, and Rocío Irene Alvarado Reyes, October 16, 2014, page 267 of the pdf. (Annex to the petitioners’ observations on the merits received on June 9, 2015). 215 Annex I. Case file. Volume XXIV, part 2, Figures concerning the measures taken in response to the disappearance of Nitza Paola Alvarado Espinoza, José Ángel Alvarado Herrera, and Rocío Irene Alvarado Reyes, October 16, 2014, page 340 of the pdf. (Annex to the petitioners’ observations on the merits received on June 9, 2015).