If they can prove that the tainted irrigation water was also used on tomatoes, federal authorities may finally have evidence backing their original focus on the fruit, and on Mexican imports.

Mexican officials retorted that the water tank had apparently not been used to irrigate crops for more than two months, and accused the FDA of breaking a confidentiality agreement by announcing findings before the investigation is complete.

The findings were announced just as Mexico’s tomato producers plan to head to court to recoup losses caused by the FDA’s warning that the recent salmonella outbreak was caused by Mexican tomatoes.

The FDA originally blamed the salmonella outbreak, which sickened more than 1,300 people since April, on certain varieties of tomatoes and released a theory that Mexican imports were the cause. On June 7, the organization released a list of “safe” providers – Mexico was not included. That same week, tomato prices plummeted in Mexico by an average 78 percent: at Guadalajara’s Mercado de Abastos, wholesale tomato prices fell from 9.33 pesos a kilo to two pesos only six days later.

The FDA exonerated Mexican tomatoes in July, after finding no evidence to support their original theory. Jalisco was the last state to be cleared. The nation’s agricultural secretariat, which has fully cooperated with the FDA investigation, recognized that there is a risk that Mexico could be used as a permanent scapegoat.

The problem goes beyond last month’s losses, tomato producers say. Mauro Jimenez, president of Jalisco’s agricultural council, expressed worry that sales of August’s tomato harvest will be severely compromised by the FDA’s “unfounded” accusations if the resulting “psychosis” among U.S. consumers continues.

Producers are considering several legal options, including complaint mediation through the North American Free Trade Agreement (NAFTA) or a direct protest to the international chamber of commerce. The first has never been attempted by Mexican businesses, but was used by U.S. fructose producers to protest a 2002 tax imposed by Mexico. The second option won Mexican cement businesses refunds from the U.S. government.

The FDA, however, is also in the hot seat, and likely to fight as passionately as Mexican tomato producers to defend its credibility. Federal health officials were grilled at a Wednesday congressional hearing over their decision to pursue tomatoes as the only suspects for weeks, only to suddenly switch focus. The salmonella Saintpaul strain responsible for the outbreak was finally found on a single Mexican-grown jalapeño in a south Texas produce warehouse last week.