Who Alerts Editors of Plagiarism?

I'm looking at the COPE flowcharts on how to handle plagiarism. One starts, "Reviewer informs editor of suspected plagiarism." A second one starts, "Reader informs editor....".

Is this an accurate picture of who informs editors of plagiarism?

A few months ago, I posted that we manuscript editors at a well-indexed journal I used to copyedit saw plagiarism in about 30% of accepted papers. (Some was very serious and some was cut-paste patch writing that could be rehabilitated.) Two evenings ago I received a call from a manuscript editor in a similar situation with the same problem. The manuscript editor asked advice on what to do. 

My advice was to document it and inform the editorial office, asking for a replacement paper to prepare for publication while the case was being handled. (At my former journal, we would usually remove the paper temporarily from the copyediting process and ask the author to rectify the situation.) 

I'm wondering if it's rare for a manuscript editor (in-house or freelance) to inform an editor of plagiarism?

Mary Ellen Kerans
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I'm a freelance copyeditor, and I'm not aware of this happening with medical journals, though that doesn't mean that it doesn't happen. However, in addition to editing medical journals, I also edit books, and your scenario happens often enough with books. It's happened with several books I've edited, and I know of several other freelancers who have reported plagiarism in their projects to the in-house editor.

Katharine O'Moore-Klopf
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I Google the first reference or the most frequent reference and have discovered a lot of cut-and-paste plagiarism this way—amazing, sometimes. Be prepared for the 'author' to insist they have re-written it in their own words!!!

Vivien Miller