Commentary on: Krane DE, Ford S, Gilder JR, Inman K, Jamieson A, Koppl R, Kornfield IL, Risinger DM, Rudin N, Taylor MS, Thompson WC. Sequential unmasking: a means of minimizing observer effects in forensic DNA interpretation. J Forensic Sci 2008;53(4):1006-7.

Sir, I share Krane et al.’s concern about the potential danger of antisuspect bias in forensic DNA analysis, and I agree that ‘‘interpretation of an evidentiary DNA profile should not be influenced by information about a suspect’s DNA profile.’’ However, judging by their letter, the incidence of such bias is unknown. It appears that we do not know that there is a problem, and, if Krane et al.’s recommended policies were adopted, we would not know whether or not any good had been done. With some exceptions (e.g., http:// www.cstl.nist.gov/div831/strbase/interlab/MIX05.htm) there has been little effort to systematically survey subjective decisions by forensic DNA analysts. The authors are to be commended for the careful thought they have brought to this issue, but I hope that compelling theory does not distract us from the need for empirical data.