MEXICO CITY -- A major Mexican drug lord's ex-fiancée was killed and a rival drug cartel carved its signature on her body, local press reported Friday, citing official sources.

A body found on December 17 in a car trunk was identified as that of Zulema Yulia Hernandez, former companion of Joaquin "El Chapo" Guzman, the leader of the powerful Sinaloa cartel who escaped prison in 2001.

The letter "Z" was carved into her skin and marked several times elsewhere on her body, in what is believed to be the signature of the "Zetas" gang, an armed branch of the Gulf cartel at war with the Sinaloa cartel.

The group was created in the 1990s by retired army officers and defectors.

No official confirmation could be obtained midday Friday.

Hernandez, 35, met Guzman in prison, after she was also sentenced for drug trafficking with the Sinaloa cartel.

Feuding drug cartels have engaged in a brutal battle for dominance, with more than 5,300 people killed this year across Mexico.

The rampant violence comes despite the deployment of some 36,000 troops across the country.