Gen. Jose Luis Chavez Garcia, the top federal prosecutor in Baja, said at the news conference that authorities were preparing a search warrant for the ranch when they were overtaken by events.
Personal vengeance was being examined as a possible motive for the killings, in a nation where inter-family enmities sometimes simmer for years before erupting into violence, especially in the countryside.
Many see the fingerprints of the drug trade in both the style of the attack--which seemed to involve well-trained and cold-blooded assassins--and the high-powered weapons employed. The killers did most of their damage with AK-47s, known here as cuernos de chivos (goat horns) because of their distinctive curved magazines. The weapons are a favorite among drug traffickers.
About a dozen assailants are believed to have sprayed the victims with gunfire as they lay face-down on a concrete patio after having been roused from their sleep. Authorities found almost 100 spent shells at the gruesome scene.
Journalists who toured the grounds late Friday encountered a tableau of grim contrasts: the strewn toys of children and a trail of bloody footprints believed to have been made by Castro after he was first wounded in his house. He later was shot with the others outdoors.
A U.S. drug enforcement agent said that while U.S. officials are still trying to piece together the story behind the massacre, they are leaning toward the theory that it was an Arellano Felix hit, in part because of the brutality.
The Arellanos, considered Mexico's most vicious cartel, have been known to break with the so-called law of the Mafia that declares family members immune to such violence.
Arellano gunmen were blamed for the death of the wife and children of a rival drug lord. And in the last few years, they have been blamed for the murder of the elderly father and the wife of a witness who implicated the cartel in a series of crimes.
"They go a step further, like the Colombian cartels," the U.S. agent said. "But it's horrendous, so many at one time. That's barbaric, even by their standards."
A veteran U.S. anti-drug official echoed those sentiments. "You have [killings] here and there, but 21 people? It's like mixing up Jonestown, Waco and the Colombian cartels. . . . What are they trying to prove with this?"
Whatever the motive, the crime has deeply shaken people in this relatively quiet corner of Baja California, a place that, until now, has escaped the gangland-style killings of Tijuana.
'The People Who Did This Are Maniacs'
Just a quarter-mile up the hill from the scene of the massacre, Leticia Rodriguez had difficulty putting the scale of her loss into words. She was related to six of the dead.
"I'm terribly sad for what happened," she said as she hung laundry. "The people who did this are maniacs to have the kind of heart to kill in that way."
A few miles down the road near the bustling hotels and restaurants of Ensenada, businessmen who cater to Southern California tourists worried that reports of the savage attack could chase customers away.
"People will only remember the headlines, 'Massacre in Ensenada,' " said Lorenzo Scott, who runs an art gallery. "People who don't come down here enough to know better will stay away."
McDonnell reported from Tijuana, Ellingwood from Ensenada and Tobar from Los Angeles. Times staff writers Ann-Marie O'Connor and Tony Perry contributed to this story.
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Drug-Related Murders in Mexico
November 1997: Gunmen open fire on Jesus Blancornelas, editor of Zeta, a Tijuana news weekly that regularly covers the drug trade. Blancornelas is seriously wounded and his bodyguard is killed.
August 1997: In Ciudad Juarez, at least 17 gangland-style killings occur after the July 4 death of Amado Carrillo Fuentes, who ruled Mexico's premier narcotics-smuggling organization. Officials are uncertain whether the violence is related to incursions by rivals of Carrillo's cartel or an internal shake-up.
March 1997: Gunmen shoot the father and wife of Jesus Alberto Bayardo Robles in Tijuana. Bayardo, now in federal prison, had implicated the alleged leaders of a Tijuana cartel in crimes.
Tijuana police find the tortured body of Felipe de Jesus Equihua, a prominent ruling-party militant. Equihua had been close to a witness in the drug-related cases of Alfredo Hodoyan and Emilio Valdez Mainero, which were due to be heard in San Diego courts.
January 1997: Hodin Gutierrez Rico, a respected state prosecutor, is murdered. He had been conducting a yearlong probe of the April 1994 assassination of Jose Federico Benitez Lopez, a reform-minded Tijuana municipal police chief.
September 1996: Jorge Garcia Vargas, Tijuana district chief of the federal anti-narcotics agency, and three federal agents who served as his bodyguards, are found strangled.
After less than a month on the job, Cmdr. Ernesto Ibarra Santes, Baja director of the Federal Judicial Police, is gunned down along with three others.