MEXICO CITY — The Mexican congressman Gabriel Gómez Michel, who was confirmed dead on Wednesday, was probably executed by a drug cartel, a state prosecutor said.

Mr. Gómez was kidnapped with an aide on Monday in Guadalajara. Their charred remains were found in a burned-out pickup the next day. The identities of Mr. Gómez and his assistant Heriberto Núñez were confirmed on Wednesday.

The authorities have so far given no motive for the murders. Mr. Gómez is the most senior politician to have been killed since Rodolfo Torre, a candidate for governor in the violence-racked northeastern border state of Tamaulipas, was killed in 2010.

Arturo Nahle, attorney general of Zacatecas State, where Mr. Gómez’s body was found, told local radio that the Jalisco New Generation cartel was probably behind the killing because of the nature of the abduction. The cartel is a relatively new gang that security experts say has made large inroads in territory controlled by more established groups.