The blood-streaked body of a Palestinian shot to death for allegedly cooperating with Israel, strung up by the ankles yesterday in downtown Ramallah, was only the latest in a list of hundreds of Arabs similarly killed by their Palestinian brethren. The al-Aqsa Brigades of Yasser Arafat\'s Fatah movement took responsibility for yesterday\'s killing - yet the silence of human-rights groups at the act was deafening. AP reports that \"dozens of collaborators have been killed by Palestinians - most gunned down in nighttime raids. Others in Palestinian Authority prisons are often sentenced after trials lasting a few hours.\" AP added that during the intifada of 1987-93, \"more than 800 suspected collaborators were killed by fellow Palestinians.\"