Aug. 7 (Bloomberg) — A former UBS AG municipal-bond executive told an ex-colleague to forget about a transaction as they discussed how to handle an expanding government probe of bond big rigging, the second man testified at trial.

Mark Zaino, who worked on the bond desk at UBS, told the federal court jury in Manhattan yesterday that Gary Heinz, one of three defendants in the municipal bond big-rigging trial, told him to "forget about" a transaction involving the Massachusetts Education Financing Authority. Zaino said he, Heinz and Michael Welty, a co-defendant, had rigged the bids for that deal.

Zaino, a key witness for the prosecution, told jurors what he thought Heinz expected him to do. "I understood that we should come up with a lie with a credible reason for the payments with respect to the Massachusetts transaction," Zaino said.