BRENTWOOD - Authorities say a native Long Islander was killed in what may have been another so-called "insider attack" in Afghanistan over the weekend. Kevin O'Rourke was a retired NYPD sergeant from Brentwood who was working as a contractor in Afghanistan. A fellow retired police officer who served with O'Rourke for 25 years says his friend was helping train Afghan forces. The firefight that cost O'Rourke's life remains under investigation. NATO officials initially reported that it appeared to be a "green-on-blue" attack carried out by Afghan forces on coalition troops. Now, officials say there may have been confusion over the source of a mortar attack that's believed to have been fired by insurgents. O'Rourke, a father of two teenage children, lived for years in Islandia and Brentwood before retiring to Florida several years ago. Former neighbors remember him as a dedicated police officer, a great neighbor and a caring father.Former LI resident killed in latest Afghanistan clash