Aeropostale Inc.’s ex-chief executive officer testified in the conspiracy trial of Christopher Finazzo that he fired the former merchandise executive in 2006 because of a secret deal with a vendor.

Julian Geiger, now CEO of Crumbs Bake Shop Inc., told jurors today in federal court in Brooklyn, New York, that Finazzo appeared to have a close relationship with South Bay Apparel Inc., a T-shirt supplier.

Finazzo is accused by the government of conspiring to overcharge Aeropostale, a New York-based retailer, and split the profits, netting him as much as $25 million from about 1996 to late 2006.

In discussions about finding lower-priced vendors for the shirts, Finazzo reacted harshly to criticism of South Bay, Geiger said on the stand.

“He was a staunch advocate of theirs,” Geiger said. He recalled that on one occasion Finazzo “took his hands” and “hit them on the table.”

“He told me I wasn’t allowed to ask him any questions about graphic T-shirts for a month,” Geiger said under questioning by Assistant U.S. Attorney Winston M. Paes.

Geiger’s testimony came in the second week of a trial before U.S. District Judge Roslynn R. Mauskopf. Finazzo is facing 16 counts, including conspiracy, mail fraud and wire fraud charges. He could be sentenced to as long as 20 years in prison if convicted of a fraud charge.