Francisco Rafael Arellano Felix, 63, the eldest brother of Mexico's once-feared Arellano Felix drug clan, was shot dead in the Baja beach resort of Los Cabos by a gunman wearing a clown costume complete with a wig and a round red nose.
Relatives confirmed the victim's identity at the scene of the crime at a rented beach house, the attorney general's office in Baja California Sur state said in a statement. He was hit by two bullets, one in the chest and one in the head.
Felix and his brothers controlled the drug trade on Mexico's border with the US in the 1990s but their Tijuana cartel was gradually weakened by the capture or killing of other leading members.
He was arrested in 1993 but released nearly 15 years later after spending time in prison in Mexico and the US.
The motive for the clown attack, and the gunmen's disguise, are still under investigation.