Officials were told in a 2008 letter they had to "promptly" address violations at the Nassau County Police Crime lab. That's more than two years before officials say they were notified of the problems.
A judge released the letter Wednesday. It was written by the then-head of the state Division of Criminal Justice Services, Denise O'Donnell.
It cited a 2007 report by a national crime lab accrediting agency. It found that the Nassau lab did not comply with standards in eight "essential" areas.
The lab was closed earlier this year. The accrediting agency placed it on probation in late 2010 for failing to meet national standards.
According to Newsday, the district attorney and former police commissioner say they never received the 2008 letter.
A state probe is under way.