Investigation of E. coli outbreak at Oregon Montessori school closed and remains a mystery

The E. coli outbreak at a West Linn Montessori school that sickened three children will remain a mystery, with health officials announcing Monday they have wrapped up the investigation without evidence pointing to the cause.

West-Linn-MontessoriInvestigators combed Heart Centered Montessori School, taking environmental samples that were tested for E. coli. All students and staff were tested as well. Those tests yielded nothing, according a news release.