CAT/C/KEN/CO/2 party should improve the terms and conditions of service for police officers to be at the same level as other security forces, and take effective measures to protect the lives of security officers. Data collection 35. The State party should establish a system to compile national statistics and should provide statistical data relevant to the monitoring of the implementation of the Convention at the national level, including data on complaints, investigations, prosecutions and convictions of cases of extrajudicial killings, enforced disappearances, domestic and sexual violence as well as on means of redress, including compensation and rehabilitation, provided to victims. Cooperation with United Nations human rights mechanisms 36. The Committee recommends that the State party strengthen its cooperation with United Nations human rights mechanisms, including by inviting Special procedures mandate holders on areas related to this report to visit the country. Other issues 37. Recalling the commitment made by the State Party during the universal periodic review in 2010 (A/HRC/15/8, para.101.3), the Committee recommends that the State party consider ratifying the Optional Protocol to the Convention against Torture and Other Cruel, Inhuman or Degrading Treatment or Punishment. 38. The Committee recommends that the State party consider making the declarations envisaged under articles 21 and 22 of the Convention. 39. The Committee invites the State party to ratify the core United Nations human rights treaties to which it is not yet a party, namely the International Convention on the Protection of the Rights of All Migrant Workers and Members of Their Families, the Convention for the Protection of All Persons from Enforced Disappearance and the Optional Protocols to the International Covenant on Economic, Social and Cultural Rights, the International Covenant on Civil and Political Rights, the Convention on the Elimination of All Forms of Discrimination against Women, the Convention on the Rights of the Child (on the sale of children, child prostitution and child pornography) and the Convention on the Rights of Persons with Disabilities. 40. The Committee requests the State party to provide, by 31 May 2014, follow-up information in response to the Committee’s recommendations related to (a) ensuring or strengthening legal safeguards for persons detained, (b) conducting, prompt, impartial and effective investigations, and (c) prosecuting suspects and sanctioning perpetrators of torture or ill-treatment, as contained in paragraphs 9, 10, 17 and 18 of the present document. 41. The State party is invited to submit its next report, which will be its third periodic report, by 31 May 2017. To that purpose, the Committee will, in due course, transmit to the State party a list of issues prior to reporting, considering that the State party has accepted to report to the Committee under the optional reporting procedure. 12