Head of Justice Unit That Oversaw Botched Stevens Case Steps Down

The head of the Justice Department unit blamed for botching the prosecution of former Sen. Ted Stevens is stepping down.

William Welch, who led the department's public integrity unit, plans to return to Massachusetts. The unit will conduct a national search to find his replacement.

"I think Bill believes it would be best for him on a personal level and best for the criminal division that at this period of time, that he wants to go back to Boston where so much of his career was based," said Lanny Breuer, assistant attorney general in the criminal division.

Breuer called Welch a "smart and thoughtful lawyer" and a dedicated public servant.

But the public integrity unit took a hit in April when Attorney General Eric Holder moved to drop the federal government's case against Stevens, the veteran Republican lawmaker from Alaska.

Stevens was convicted on seven felony counts of corruption in the fall of 2008 and subsequently lost his bid for re-election, but Holder decided to abandon the case due to prosecutorial misconduct.

Breuer defended the department Wednesday.

"Our prosecutors throughout the country act in good faith and do extraordinarily good work," he said. "There are very, very few examples of misconduct. Like anything, there are examples of error, and in a day in age of ever-more complex litigation and cases that have sometimes thousands or tens of thousands of pages of documents if not more, errors can be made. So what we want is a comprehensive approach to minimize the chance of error."

He said that would include more training for staff.

Fox News' Mike Levine contributed to this report.