The National University of Singapore launched an investigation in early 2011 into all 70 papers produced there by immunologist Alirio Melendez after being "disturbed" by its discovery of research misconduct relating to two of his papers.
In a statement issued on 20 December, Singapore says its investigation committee has "uncovered evidence of fabrication, falsification, or plagiarism associated with 21 papers, including the two in the original allegation".
"Based on similarities in the pattern of misconduct and in some cases sole authorship of questionable papers, [the committee] concluded that Dr Melendez has committed serious scientific misconduct. The committee found no evidence indicating that other co-authors were involved in the scientific misconduct," it says.
It notes that some of the "questionable" papers have already been retracted, and the university has "started the process of informing the relevant authors and journals about the problems" in the others "to ensure that the public scientific record will be corrected".
However, Nature that the university has declined to release the investigating committee's report.
Dr Melendez's current whereabouts are unknown. When the Singapore investigation was originally announced he told Times Higher Education that "some of the data [in the papers under suspicion] appear to have been duplicated/plagiarised or accommodated to fit a few papers", but he insisted that he had not personally committed any misconduct.
The University of Glasgow, where he was a senior lecturer between 2007 and 2010, and the University of Liverpool, where he was chair of immunopharmacology until his resignation in November 2011, also announced concurrent investigations into work he carried out while in the UK.
Glasgow's investigation concluded last August, but a spokesman would only say there was "no evidence that our current staff contributed, falsified or duplicated data to any publications co-authored with [him]". Liverpool's investigation was abandoned following his resignation since none of the work in question was carried out there.