Washington ? Spinach found in the refrigerator of a person sickened by E. coli was contaminated with the bacteria, the “smoking gun” that investigators have sought for the origin of the deadly outbreak, health officials say.

Federal and state investigators on Wednesday focused their hunt to nine farms in California’s greater Salinas Valley, said Dr. Mark Horton, the state public health officer. They also were checking processing plants, said Horton, who called the bag of tainted Dole baby spinach the “smoking gun” in the case.

Despite closing in on the source of the bacteria as likely somewhere in Monterey, San Benito or Santa Clara counties, officials continued to recommend that consumers not eat fresh spinach.

“Yesterday we had it down to California. Today we’ve got it down to three counties,” said Dr. David Acheson of the Food and Drug Administration’s Center for Food Safety and Applied Nutrition. “We want it down to a salad bowl and eventually a spinach leaf.”

The tainted bag came from a refrigerator in New Mexico, said Department of Health officials for that state. A person who ate some of the leafy greens became one of 146 people in 23 states sickened by the outbreak. One person has died.

The spinach tested positive for the same strain of E. coli linked to the outbreak, Acheson said. Dole is one of the brands of spinach recalled Friday by Natural Selection Foods LLC, of San Juan Bautista, Calif.

Government and industry officials are working on how to allow spinach grown elsewhere back on the market, Acheson said.