A Greek Cypriot army officer pleaded guilty on Monday to seven counts of premeditated murder in a serial killing case that has shocked the Mediterranean island.Nicos Metaxas, 35, was led into a Nicosia court under heavy security and stared grimly at the ground as a prosecutor read out a string of charges, including kidnapping and the killings of five women and two of their daughters – all foreigners.Holding back tears, he pleaded guilty to the accusations one by one.After the prosecutor read a…