CHULA VISTA, Calif.  Eduardo Tostado was a prosperous man whose businesses and pleasures straddled the coastal border. He owned a big house and a used-car lot in the San Diego suburbs, and a seafood restaurant in Tijuana.

He was also part of the border underworld, the authorities say  a high-ranking member of the Mexican drug cartel driving much of the United States’ illegal marijuana trade and the cascade of violence in a 40-year drug war. Some evenings, Mr. Tostado drank tequila at the Baby Rock club in Tijuana or sipped Scotch at the Airport Lounge in San Diego. He socialized mainly with men he knew well and women he knew not at all.

His wife, Ivette Rubio, was aware of this, and they were having problems in their marriage. So when Mr. Tostado called her in June 2007 to say he had been kidnapped and needed her to sell their house to pay a ransom, she did not believe him.

“You got drunk,” she said, “and you went out, and you didn’t come to sleep in the house.”

Click, the phone went dead.