Anthony Chiasson was unknown outside of Wall Street before his arrest in January on insider trading charges.
A co-founder of Level Global and the head of research there, Mr. Chiasson typically resided in the shadow of his more prominent partner, David Ganek.
Now, it appears, Mr. Chiasson is making an effort to pull in Mr. Ganek as part of his defense strategy. In a letter sent to the federal judge overseeing the case, lawyers for Mr. Chiasson said they planned to show jurors an analysis from an expert witness showing that Mr. Ganek traded in the same stocks during the same periods that their client did.
Mr. Chiasson's lawyers, Greg Morvillo and Reid Weingarten, do not accuse Mr. Ganek of trading on inside information. Indeed, Mr. Ganek, who decided to shutter Level Global last year following a raid by federal agents, has not been accused by investigators of any wrongdoing.
But any evidence that shows that Mr. Ganek bought and sold the same shares a round the same time that Mr. Chiasson did could provide reasonable doubt to jurors. Beyond addressing the trading pattern at the firm, the lawyers' letter to the judge, Richard J. Sullivan of Federal District Court for the Southern District of New York, indicated that the defense planned to use the testimony of Mukesh Bajaj, the founder of AFE Consulting, to show that public information was readily available to support the tips that Mr. Chiasson is accused of trading on.
“After an exhaustive two year investigation and on the eve of trial, what speaks for itself is that the government hasn't charged anyone else from the fund,†said Davidson Goldin, a spokesman for Mr. Ganek.
The government, for its part, is arguing that Mr. Ganek's trades should not be admissible because they are not part of the case. At Level Global, three people shared trading oversight, which also would make it difficult for the defense to parse out what trading was ordered by whom.
M r. Ganek and Mr. Chiasson cut their teeth trading for SAC Capital, the hedge fund behemoth run by the billionaire Steven A. Cohen. The men decided to start their own fund in 2003, and quickly raised a handsome sum for investors eager to put money with the rising stars. Mr. Ganek, a trader and portfolio manager, captured headlines for his lavish spending, including for a home in one of Manhattan's most exclusive buildings and his substantial modern art collection.
Mr. Chiasson, for his part, stayed under the radar. He had no overly expensive habits and didn't serve on any of the boards that his partner did, though he remained involved in his high school and college alma maters.
When the hedge fund sent out a letter to investors stating its intention to return money to them, Mr. Ganek's was the sole signature at the bottom. A spokesman for Mr. Ganek said at the time, nearly a year before Mr. Chiasson was charged, that the gesture had nothing to do with any impendin g criminal action.
But of all the insider trading cases the government has brought, from a hedge fund tycoon to a former Goldman Sachs board member, Mr. Chiasson's case is the biggest. He and others are accused of making $67 million trading based on insider tips related to Dell and Nvidia.
