FRANKFURT — Fiat Chrysler Automobiles, one of the world’s biggest carmakers, said on Thursday that it was in talks with the Department of Justice to settle an investigation into diesel deception, as growing evidence points to the carmaker’s use of illegal software to evade emissions tests.

The settlement talks add to the pressure on Fiat Chrysler at a time of meager profitability.

The German carmaker Volkswagen, which faced a similar scandal, has been hit with billions of dollars of settlements and fines, and seen several executives investigated or charged. Though Fiat Chrysler’s financial damage is unlikely to be as costly as Volkswagen’s, the emissions cheating, if proved, could still be expensive.

The investigation is following much the same path.

In January, the Environmental Protection Agency accused the carmaker of violating clean air rules in about 100,000 Dodge Ram and Jeep Grand Cherokee vehicles. The Justice Department has since been looking into the matter.

Now, a new academic study is lending credence to the claims.

Researchers from the University of the Ruhr in Bochum, Germany, and the University of California, San Diego, said they found evidence of a so-called defeat device in a diesel Fiat 500X, a compact S.U.V. sold in Europe. Software in the engine’s computer reduced pollution controls 26 minutes after the car was started, according to the study. A standard emissions test procedure lasts a little less than 26 minutes. Fiat Chrysler declined to comment on allegations of cheating in the 500X.