A jury has reached a mixed verdict in the trial of three long-retired Philadelphia detectives who were accused of lying about evidence in a 1991 homicide case that later ended with an exoneration.

Three long-retired Philadelphia detectives are on trial this week in a perjury case that asks whether police should be held responsible for alleged misconduct in exoneration cases.

Nearly 3,500 people have been exonerated of crimes in the U.S. since 1989, and $4 billion has been paid in compensation.