Polish security services detained 19-year-old Mateusz W. on suspicion of contacting the Islamic State and charged him with preparing a Christmas market attack that could have caused mass casualties, following earlier reports that he was arrested in late November.Officers from the Internal Security Agency (ABW) seized data carriers and items related to Islam, prosecutors say he faces between 12 years and life in prison if convicted, a court ordered his detention for three months and the Catholic University suspended him pending investigation while Jacek Dobrzynski linked the case to a mid-June Olsztyn plot and warned the public amid concerns after a Sydney incident.