Former SAC Capital Advisors LP portfolio manager Mathew Martoma asked a judge to force the government to turn over evidence that he says can help him beat insider trading charges as his case goes to trial next month.

Martoma in a request filed in federal court in Manhattan, N.Y., said prosecutors have failed to provide him with communications between the government and lawyers for the two scientists who allegedly gave him non-public information about drug trials and who will be key government witnesses.