About 5,200 pounds of ground beef products are being recalled because of fears they're infected with a dangerous strain of E. coli.

The products were distributed in seven states and are identifiable by the words "Est. 2424" found inside the USDA inspection mark

The ongoing search for the source of a deadly E. coli outbreak in spinach has become a criminal investigation, as federal agents raid two California produce companies.

Agents from the Food and Drug Administration (FDA) and FBI have begun searching for evidence as part of a probe, sanctioned by the federal Food, Drug and Cosmetic Act, which makes the production or sale of "adulterated foods" a crime

In the wake of the ongoing probe into the source of a nationwide E. coli outbreak linked to tainted spinach, the Federal Bureau of Investigation raided two Salinas Valley produce companies.

On Wednesday, the FBI and the Food and Drug Administration's criminal investigations office issued search warrants for the Natural Selection Foods LLC plant in San Juan Bautista and Growers Express in Salinas to investigate if they violated food safety and environmental laws

While investigating California farms for the source of the E.coli outbreak in spinach, investigators found E. coli in cattle feces.

The fecal samples are currently being tested to see if it is the same strain making hundreds sick nationwide. The test results will not be available for another couple days, according to Deputy Director of the California Department of Health Services Kevin Reilly

According to the U.S. Food and Drug Administration (FDA), "all spinach implicated in the current outbreak has traced back to Natural Selection Foods LLC of San Juan Bautista, California."

The findings come after a comprehensive investigation by the FDA, the State of California, the Centers for Disease Control and Prevention (CDC) and the United States Department of Agriculture (USDA) into the outbreak which has infected 187 people, causing 97 hospitalizations and one death