Speculation that the Ashkenazi arose from Khazar stock surfaced in the later 19th century and has met with mixed fortunes in the scholarly literature. In late 2012 Eran Elhaik, a research associate studying genetics at the Johns Hopkins University School of Public Health, argued for Khazar descent in his paper The Missing Link of Jewish European Ancestry: Contrasting the Rhineland and the Khazarian Hypotheses. A 2013 study of Ashkenazi mitochondrial DNA found no significant evidence of Khazar contribution to the Ashkenazi Jewish DNA, as would be predicted by the Khazar hypothesis.
Is there an answer to this question (If it cannot be answered, say "unanswerable"): Did Eran Elhaik, from Johns Hopkins University School of Public Health argue for or against Khazar descent?
argued for Khazar descent