A jury has asked to listen again to wiretaps that Manhattan prosecutors call the smoking gun in the biggest-ever insider trading case involving hedge funds.

The FBI secretly recorded the phone calls of hedge fund manager Raj Rajaratnam and other Wall Street insiders talking about the financial prospects for publicly traded companies.

Prosecutors say the recordings prove that Rajaratnam was trading on inside tips about earnings and mergers before they were announced. They allege he made tens of millions of dollars that way.

The 53-year-old defendant has pleaded not guilty to conspiracy and securities fraud charges. Twenty-one other defendants have pleaded guilty.

Federal jurors were in their second day of deliberations on Tuesday when they returned to the courtroom to rehear the batch of recordings.