A man believed to be Heriberto Lazcano Lazcano was killed last week, but the body was stolen.

Story highlights

Investigators will conduct DNA tests to confirm the killing of the Zetas leader

Police guard a cemetery in central Mexico as authorities exhume his mother's remains

Authorities have said there's no doubt they killed Heriberto Lazcano Lazcano

The cartel chief's body was stolen from a funeral home

Mexico City CNN  — 

Investigators exhumed the mother of one of Mexico’s most notorious cartel kingpins Monday, two weeks after thieves apparently made off with her son’s body before authorities could conclusively confirm his identity.

Now they plan to do DNA tests to verify that the man they killed in a gunbattle earlier this month was Heriberto Lazcano Lazcano, leader of the Zetas drug cartel, Mexico’s attorney general’s office said.

Masked federal police Monday guarded the cemetery in central Mexico that houses the mausoleum containing the remains of Lazcano’s mother, Mexico’s state-run Notimex news agency reported.

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It was the latest chapter in a dramatic saga that has cast a cloud of mystery over what could be one of the biggest accomplishments of outgoing President Felipe Calderon’s crackdown on cartels.

Mexican authorities have said they have no doubt they killed Lazcano, thanks to fingerprints and photograph evidence. But additional tests will allow them to reach 100% legal certainty, prosecutors said.

“Taking tissue samples (from a direct family member) is necessary to complete laboratory studies of the genetic fingerprint, according to the most modern and advanced protocols for identifying people,” the office said.

On October 8, authorities proudly trumpeted the death of Lazcano, who was known as “El Lazca.”

The next day, they revealed they no longer had his body; gunmen had stolen it from a funeral home.

They also said that members of Mexico’s navy shot him dead without realizing that the man in the suspicious car they’d chased outside a local baseball game on a Sunday afternoon was the head of the ruthless Zetas cartel.

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“Two people were killed, but for us, they were just two more criminals. We had no clue that it was El Lazca,” Vice Adm. Jose Luis Vergara, a spokesman for the navy, said in an interview with MVS Radio shortly after authorities announced the news.

Vergara said investigators thought he was “a criminal, not even a capo, most likely a hit man in the town or something like that.”

Officials said a fingerprint match after the autopsy confirmed he was the man Mexico’s president described as “one of the most important and most dangerous” people on the country’s list of most wanted criminals.

The United States and Mexico combined had offered rewards of more than $7 million for information leading to his capture.

Lazcano was a onetime special forces soldier who became a founding member of the Zetas, a group accused of some of the most violent atrocities that have come to define the drug war.

Lazcano, 37, joined the Mexican armed forces in 1991 and was part of its elite airborne special forces group, dedicated to battling drug cartels.

Soon after, Lazcano and several other special forces members were recruited by the Gulf cartel to create its enforcement arm, the Zetas.

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After the partnership ended in 2010, the Zetas split into a major drug trafficking organization and have since branched out into extortion, kidnapping and human smuggling.

Analysts have said it is unclear what impact Lazano’s death will have on the Zetas.

The cartel had been in the midst of a bloody turf war with its former employer, the Gulf cartel, and also with the Sinaloa cartel.

The fight for access to lucrative smuggling routes in northern and central Mexico has left thousands of civilians dead.

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CNNMexico.com and CNN’s Catherine E. Shoichet and Mariano Castillo contributed to this report.