Two months ago, news outlets reported that an Oregon farmer had found Roundup herbicide-resistant wheat growing in his field. He hadn't planted it. In fact, nobody sells it — Monsanto tested such wheat eight years ago, but never sought federal approval for it. So what happened? After two months of investigation, here's what we do know: It doesn't seem like GMO wheat is invading the US. Testing has yet to turn up evidence of this wheat anywhere else in the country. What we don't know: Why a research plant that never went to market would pop up in a single, unrelated field almost a decade later. Experts' best guess is some kind of mix-up, where a small amount of research seed got mislabeled and later sold. Meanwhile, Monsanto is suggesting deliberate sabotage.