-57 ERJO, CPT, SMR and others (HMIP, Expectations: Criteria for assessing the treatment of children and conditions in prisons, Version 4, 2018, available at:https://www.justiceinspectorates.gov.uk/ hmiprisons/wp-content/uploads/sites/4/2020/02/Childrens-Expectations-FINAL-Dec-2019.pdf, accessed 9 October 2020. 3.3.2. Sources of information and preparation for the monitoring visit Human rights monitoring in general and detention monitoring in particular should use as many sources as possible to fulfil its tasks. Of course, the major source of information is the visit to the detention facility, but also collecting information on the specific institution, on criminal detention in general, and on the groups and individuals in a situation of vulnerability in detention, which starts long before the visit. It is in fact an essential component for preparation for the visit, and has a significant bearing on its quality. What sources of information can we check while preparing for the visit? It would certainly be of help to collect in advance basic background information about the detention facility – its capacity, the most recent number of detainees held, the level of overcrowding, the number of staff and its type, recent renovations, new programmes introduced, etc. The NPM should be able to obtain such information officially. Another important source are existing reports on the specific detention facility and on similar detention facilities prepared by local and international monitors with a similar mandate (the CPT, the SPT, NGOs). Where possible, the monitoring team should meet with the delegations which took part in the visits and prepared the report, in order to inquire for more information. Such meetings can direct the team to vulnerable groups and persons whose situation had not been presented in sufficient detail in the report. It should be a must for the NPM team to check in advance of the visit all complaints of prisoners from the detention facility they plan to visit and to check additional information to which the complaints may direct. Such complaints, especially when they originate from persons in a situation Prisoners in a Situation of Vulnerability