Updated

A New York City prosecutor has embarked on one of the country's most ambitious efforts to review the murder cases of defendants who claim they were wrongly convicted.

Brooklyn District Attorney Kenneth Thompson's review unit is re-examining about 90 mostly homicide cases from the 1980s and 1990s. Nearly 60 have links to one detective.

Other prosecutors' offices also have launched conviction review projects. But exoneration experts say few, if any, have tackled such a large and open-ended review of cases, all at once. They date to an era when New York's murder rate was soaring and the legal system was stretched to the limit.

Brooklyn prosecutors have persuaded judges to throw out six convictions so far this year. More dismissals are expected, but prosecutors say the process can be complex.