Is Subway selling real tuna or is it fake? Test finds no tuna DNA.

After a class-action lawsuit was filed against Subway in January alleging that its tuna was fake, The New York Times launched an investigation on whether the allegations were true or false.

In the article, journalist Julia Carmel wrote that she used commercial lab that could test a sample of tuna from different sandwiches across California Subways. Carmel found herself on the phone with a spokesman for a lab that specialized in fish testing.

"He agreed to test the tuna, but asked that the lab not be named in this article, as he did not want to jeopardize any opportunities to work directly with America's largest sandwich chain," Carmel wrote.

For about $500, Carmel wrote that his lab would conduct a PCR test, which would make copies of a specific DNA sample, and this test would show if Subway's tuna included one of five different tuna species.

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After more than a month of waiting, the results came in.

The lab told Carmel that there were two conclusions: either the meat was too heavily processed to be identified, or there was simply no tuna DNA to begin with.

However, there are other factors to consider, including the fact that once tuna is cooked, its DNA becomes denatured, which would make it difficult to identify a fish's characteristics.

"A recent New York Times report indicates that DNA testing is an unreliable methodology for identifying processed tuna. This report supports and reflects the position that Subway has taken in relation to a meritless lawsuit filed in California and with respect to DNA testing as a means to identify cooked proteins," the sandwich chain said in a statement to Business Insider. "DNA testing is simply not a reliable way to identify denatured proteins, like Subway's tuna, which was cooked before it was tested."

According to The Washington Post, the class-action lawsuit – filed in the U.S. District Court for the Northern District of California – alleged that based on independent lab tests of "multiple samples" taken from Subway locations in California, the tuna is "a mixture of various concoctions that do not constitute tuna."

The two plaintiffs of the complaint, Karen Dhanowa and Nilima Amin, sued Subway for fraud, intentional misrepresentation, unjust enrichment and other claims, according to The Washington Post. Dhanowa and Amin argued they "were tricked into buying food items that wholly lacked the ingredients they reasonably thought they were purchasing."

This article originally appeared on USA TODAY: Subway tuna DNA test: No tuna in sandwiches, New York Times finds