[University of Michigan Law Professor Samuel] Gross co-authored a report on the database that pulls together statistics on exonerations from January 1989 through February 2012. While the database is constantly updated and new exonerations are being added all the time, the report focuses on the 873 individuals whose cases had been filed before March. Gross and his report co-author, University of Michigan law school graduate Michael Shaffer, discovered correlations in the types of crimes and reasons for wrongful convictions.
- Fabricated crimes.False convictions in child sex abuse cases were usually due to fabricated crimes; sometimes a divorced parent told a child to make up lies about an ex-spouse abusing them, or police or a therapist convinced a child to say something that wasn't true.
- Eyewitness mistakes. In adult rape cases, for example, false convictions were typically based on eyewitness mistakes, "more often than not, mistakes by white victims falsely identifying black defendants," the report said.
- Misconduct by authorities. For homicides, misconduct by authorities was the second-biggest cause of false convictions, just behind false eyewitness accounts.