The Mexican Navy says tests confirm that a man killed in a shootout with marines was Heriberto Lazcano, the head of Los Zetas drug cartel.
Officials said comparisons with fingerprints held on their database showed it was the drug boss.
In a reference to reports that the body was missing, they said the body had been given to local authorities.
Lazcano is a founder of Los Zetas which has been implicated in a string of mass killings and kidnappings.
His death would be a victory in the fight against cartels, analysts say.
Lazcano was killed on Sunday in the northern state of Coahuila but his identity had not been confirmed until now.