[JURIST] Lebanon [JURIST news archive] has arrested three former pro-Syrian security chiefs, and the head of the presidential guard Mustafa Hamdan turned himself into authorities after an arrest warrant was issued for him in connection with the killing of former Prime Minister Rafik Hariri [Wikipedia profile], sources said Tuesday. The four men were brought before the UN commission investigating the killing, while several others were arrested and another warrant was issued for pro-Syrian MP Nasser Qandil. The flurry of arrests and warrants are the first major break in a six-month investigation into the massive bombing that killed the former premier and left the country shaken. The news comes shortly after Syria was criticized for failing to cooperate with the UN investigation [JURIST report] led by German prosecutor Detlev Mehlis. Syria [JURIST news archive], which has long held significant influence on Lebanon, has since pledged support for the investigation [JURIST report] and reiterated claims that it was not involved in the bombing. The Arabic News has local coverage. AFP has more.