Are MA prosecutors witholding evidence

The chief judge of the US District Court in Massachusetts is threatening to sanction a federal prosecutor for what he characterized as the latest "egregious failure" of the US attorney's office to disclose evidence that could have helped clear a defendant.
"The egregious failure of the government to disclose plainly material exculpatory evidence in this case extends a dismal history of intentional and inadvertent violations of the government's duties to disclose in cases assigned to this court," Wolf, a high-ranking prosecutor in the office in the 1980s, wrote in his 42-page ruling.
He listed at least nine major cases he presided over during the last two decades in which prosecutors working for Michael Sullivan and his predecessors allegedly withheld important evidence. In several instances, the jurist, 62, wrote, the misconduct led to mistrials and convictions that were overturned.

Link:http://www.boston.com/news/local/massachusetts/articles/2009/01/27/judge_chastises_federal_attorney/