AUTLAN, MEXICO - Inspectors are collecting soil, water and produce samples, reviewing export logs and combing packing plants in three major tomato-growing states in Mexico.

But the U.S. Food and Drug Administration appears no closer to finding the source of a mysterious salmonella outbreak that has sickened more than 900 people nationwide. The FDA is not even 100 percent sure that tomatoes are the cause -- adding peppers and cilantro Saturday to its list of foods under investigation.

A team of three FDA inspectors has gone through five farms in the western states of Jalisco and Sinaloa in the past two weeks, looking at all aspects of tomato production: the greenhouses where they are grown, the packing plants where they are shut into boxes and the shipping methods for the trip north to the United States. They also plan to visit Coahuila state.

The results can't come too soon for the three Mexican states that were targeted by the FDA, along with farms in Texas and Florida.

Bonanza 2001 farm in Autlan, Jalisco, has hundreds of tons of tomatoes sitting in storage near the Texas-Mexico border as demand has plummeted, said spokesman Luis Almejo.

Sinaloa growers also face big losses.

"We're demanding that they release those results as soon as possible so that Sinaloa can be cleared of any suspicion," said Manuel Tarriba, president of Sinaloa's Tomato Growers Association.

The outbreak, which began in April, has affected 943 people in 40 U.S. states, according to the Centers for Disease Control and Prevention. There have been 225 cases reported since June 1 -- evidence that the source likely has not been contained.