Lawyers for former Bear Stearns fund manager Matthew Tannin have asked a judge to prohibit prosecutors from introducing evidence at his criminal trial regarding the erasure of his personal email account in 2008, calling it an "eleventh-hour smear."

In a letter Monday, Susan Brune, a lawyer for Tannin, said the government's evidence has failed to establish "that Mr. Tannin destroyed any documents" and Tannin and his counsel have preserved all documents.

At a hearing last week, prosecutors from the U.S. Attorney's office in Brooklyn said that they had received a letter from Google Inc. (GOOG) indicating Tannin's Gmail account was erased in March 2008.

In a letter filed with the court on Saturday, prosecutors said the account was erased "during the pendency of the criminal investigation" and after having received a subpoena for documents in a separate 2007 civil case by the U.S. Securities and Exchange Commission.

"There is no requirement in law or in common sense that dictates that a person under a subpoena must keep his personal email account at a third-party email provider open in perpetuity," Brune said in her letter. "That Google has apparently stopped maintaining the emails that were available on its server for a lengthy period of time after the collapse of the funds is not evidence of any impropriety and is simply not relevant to any issue in trial."

Brune asked U.S. District Judge Frederic Block in Brooklyn to reject the government's request.

A spokesman for the U.S. Attorney's office in Brooklyn declined comment Monday.

Tannin and Ralph Cioffi, former managers of two high-profile bond portfolios in Bear Stearns' asset-management unit, have been charged with conspiracy, securities fraud and wire fraud. Cioffi also has been charged with insider trading.

They have denied wrongdoing. Jury selection is set to begin in their case on Oct. 13.

The July 17 letter from Google indicated there had been no recent activity in Tannin's Gmail account and the account had been deleted. A copy of the letter was filed as part of Brune's submission.

"Therefore we are no longer able to extract the information requested in the search warrant," the letter said.

In her letter, Brune said a user no longer has access to a Gmail account after it is closed or the email messages in the account. Google may maintain copies of the contents of the closed accounts for up to 60 days on its active server and for unspecified periods on its backup servers, said Brune, citing Google policy.

"Apparently, judging from the Google letter, in or about July 2009, more than two years after the collapse of the funds and approximately 21 months after the government had been informed of the account, the government obtained a search warrant directed to Google," Brune said. "By that late date, as far as we can tell from Google's letter, consistent with its published policies, Google had removed the contents of the account from the Google servers."

Brune said Tannin's computers have been electronically copied and preserved and the contents of any Gmail accounts or other documents would likewise have been preserved.

"To suggest otherwise before a jury would be to mislead and to intrude on Mr. Tannin's constitutional rights," Brune said.

The government has alleged Cioffi and Tannin encouraged investors to continue to put money in the funds while privately expressing concerns about their outlook months before their collapse.

The funds - the Bear Stearns High Grade Structured Credit Strategies Master Fund and the Enhanced Fund - imploded in June 2007 as credit markets contracted, costing investors more than $1 billion.

The closing of the funds marked the beginning of big problems for Bear Stearns, which was forced to sell itself to JPMorgan Chase & Co. (JPM) after being pushed to the brink of failure because of a liquidity crunch in March 2008.

Shareholders approved the sale of the 85-year-old investment house to JPMorgan Chase for just $1 billion in May 2008. Bear Stearns had a market value of $20 billion in January 2008.

-By Chad Bray, Dow Jones Newswires; 212-227-2017; chad.bray@dowjones.com