EMMA FARGE and ANGUS MCDOWALL EUROPEAN Union backing for Libyan authorities who stop and detain migrants means the bloc has "aided and abetted" rights violations against migrants, an investigator for a U.N. mission said. The EU and member states have supported and trained the Libyan coastguard, which returns migrants stopped at sea to detention centres, and have funded Libyan border management programmes via the Italian government. The investigator, Chaloka Beyani, was speaking after a U.N. fact-finding mission presented a report saying crimes against humanity were carried out against migrants in detention centres. "Although we're not saying that the EU and…