By Brendan O’Brien and Barbara Goldberg (Reuters) – An off-duty police officer accused of placing his knee on the neck of a 12-year-old girl to restrain her after a school fight in Kenosha, Wisconsin, is under investigation and remains employed, the city’s police department said in a statement. The March 4 incident at Lincoln Middle School drew fresh public attention after the city’s school district, which employed Shawn Guetschow as a part-time security guard when he was off duty from the city police force, publicly released video of it on Friday. It comes the year after former Minneapolis po…