A comprehensive study of 328 criminal cases over the last 15 years in which the convicted person was exonerated suggests that there are thousands of innocent people in prison today, according to the New York Times.
Almost all the exonerations were in murder and rape cases, and that implies, according to the study, that many innocent people have been convicted of less serious crimes. But the study says they benefited neither from the intense scrutiny that murder cases tend to receive nor from the DNA evidence that can establish the innocence of people convicted of rape.
Prosecutors, however, have questioned some of the methodology used in the study, which was prepared at the University of Michigan and supervised by a law professor there, Samuel R. Gross. They say that the number of exonerations is quite small when compared with the number of convictions during the 15-year period. About 2 million people are in American prisons and jails.
The study identified 199 murder exonerations and 120 rape exonerations. Only nine cases involved other crimes.
The study, which will be presented Friday at a conference of defense lawyers in Austin, Tex., also found that different factors contributed to wrongful convictions in rape and murder cases.
Some 90 percent of false convictions in the rape cases involved misidentification by witnesses, often across races. On the other hand, the study found that the leading causes of wrongful convictions for murder were false confessions and perjury by co- defendants, informants, police officers or forensic scientists.