This encouraged them in their quest to create a blood "fingerprint," a unique blood profile that could be used in legal and criminal matters. Wiener pioneered much of the type of blood testing that has now, in the age of DNA, become commonplace. Along with his work in his Brooklyn lab, Wiener also did a considerable amount of work in a Manhattan lab where he concentrated on forensics, assisting the police in numerous investigations by analyzing the blood (or related fluids) of those involved.