The report, which analyzes illicit drug trends through 2012, also notes that cocaine availability was down across the United States. It offered various possible reasons for the decline, including cartel versus cartel fights over drug routes in Mexico, declining production in Colombia and various anti-narcotics strategies that have put more heat on the groups that control production and shipment of the product.

The yearly report, released Monday and known as the National Drug Threat Assessment Summary, is an effort to describe “the threat posed to the United States by the trafficking and abuse of illicit drugs.”

The report is a synthesis of quantitative data and survey feedback from more than 1,300 state and local law enforcement agencies. Among other things, it provides an updated profile of the seemingly intractable user-pusher relationship that has developed between the United States  and its southern neighbor.

According to the report, the amount of heroin seized at the southern U.S. border increased 232% between 2008 and 2012 — apparently the result of greater Mexican heroin production and a growing incursion by  Mexican traffickers into U.S. markets. It notes that the U.S. is experiencing a “sizable increase” in the number of new heroin users.

Methamphetamine seizures at the Mexican border, meanwhile, increased fivefold in the same time period, although the report notes that U.S. demand and abuse data for meth appeared to remain stable.

The trouble with meth is most acutely felt in the West: The report notes  that 2011 arrest data showed that large percentages of arrestees in Western states tested positive for meth, with rates much lower in the East. For example, 42.9% of men arrested in Sacramento tested positive for methamphetamine; in Washington, DC, that number was 0.4%.

Marijuana continues to be Americans’ illicit drug of choice. Smuggling from Mexico has remained “consistently high” for 10 years, the report says, while U.S. domestic production is on the rise — in part due to large-scale U.S. growing operations controlled by Mexican traffickers.

The U.S. government appears to be tolerating recent decisions by voters in Washington and Colorado to legalize marijuana for recreational use in those states. But the plant remains classified as a dangerous and illegal controlled substance under federal law, and the report warns, darkly, that drug cartels will “increasingly exploit the opportunities for marijuana cultivation and trafficking created in states that allow ‘medical marijuana’ grows and have legalized marijuana sales and possession.”

The report notes the continued decline of availability of cocaine in the U.S., a trend that began in 2007. The majority of cocaine that ends up in the U.S. is of Colombian provenance, and much of it must first travel through Mexico. The United Nations has noted a decline in Colombian coca production, and U.S. officials have credited the success of Plan Colombia, the United States’  multibillion-dollar drug-fighting effort in Colombia, which includes, among other things, military aid, crop eradication programs and social spending.

Critics of U.S. drug policy fear that the pressure on Colombia is only pushing production to other countries, like Peru, a phenomenon commonly known as the “balloon effect.”

The title of “fastest growing drug problem” in the U.S., according to the report, goes to prescription drugs, including painkillers, which are often obtained domestically at unscrupulous “pill mills,” or from online sellers.

The report says that recent state laws to crack down on pill mills could create another kind of balloon effect, forcing “abusers and distributors to obtain [prescription drugs] in other areas of the country where little or no legislation currently exists … or in other countries such as Canada and Mexico.”

Photo: Vigilantes arrive in the town of Pareo, in Mexico’s Michoacan state. The Knights Templar drug cartel controls parts of the state, and a “self-defense” movement has arisen to fight it. (Agencia Esquema /November 16, 2013, via LA Times)

The victims, discovered Sunday, include two girls, ages 4 and 6; a 7-year-old boy; three women, ages 25, 30 and 60; and two men, ages 30 and 40, according to the Chihuahua prosecutor’s office. As of Monday, no suspects had been detained.

The newspaper El Diario reported that the dead, who had been bound and gagged with packing tape, were members of a Jehovah’s Witness group. Fellow congregation members stumbled onto the crime scene when they stopped by the family’s house to check on them after they had failed to show up for Sunday religious services, the paper reported.

Friends of the family also found a 3-month-old baby girl in the house who had been spared in the assault, according to media reports.

The gruesome discovery, combined with a Sept. 22 shooting that left 10 dead at a suburban house party, is likely to amplify the debate about the tenuous security gains Juarez has enjoyed in recent months.

Four years ago, the city was ranked, by some measures, as the most violent in the world, due in large part to a running turf war between the Sinaloa and Juarez drug cartels. In 2009, a homicide occurred on average about every three hours, and a quarter of the population fled the city.

The Mexican federal government, led by then-PresidentFelipe Calderon, sent in thousands of troops, and intensified a massive security and social-programs push after another massacre on Jan. 31, 2010, in which 15 celebrants at a house party were slain by gunmen, sparking a national outrage.

Last year saw a significant decline in slayings. Officials have been touting the influence of new classrooms, programs for troubled youth, and upgraded tools and training for police — some of which was funded by the U.S. government.

But many suspect that the decline is due largely to the Sinaloa cartel’s victory over its rivals.

It was unclear if the latest massacre was connected to drug cartel activity. But for many residents, the immediate focus was not on the motives, but on the human toll.

“Who in the hell … would assassinate three kids?” wrote one commenter on the El Diario website. “Not even irrational beasts would do such a thing.”

Photo: Forensic experts investigate at a house in which eight people were stabbed to death in the Mexican city of Juarez. (EPA, via LA Times)

MEXICO CITY — Joaquin Hernandez Galicia, the former Mexican oil union boss who rose to control a political empire built on patronage and intimidation but was eventually dethroned by a Mexican president wary of his vast power, died Monday. He was 91.