Updated

TOLUCA, Mexico -- A suspect was arrested Thursday in three shootings that killed 20 people on the outskirts of Mexico City, attacks authorities blame on a brutal cartel trying to seize drug-dealing territory in the capital.

Juan Carlos Vasconcelos, 24, is suspected of leading a team of hit men for La Familia cartel, said Alfredo Castillo, attorney general of Mexico state, which borders the capital. He was arrested along with two alleged accomplices.

Castillo said Vasconcelos was behind three shootings in two sprawling, gritty neighborhoods on the outskirts of Mexico City. The first left five people dead on Jan. 8. Another killed eight people Jan. 16 and the third left seven dead Feb. 13.

Masked police paraded Vasconcelos shirtless before television cameras, showing his many tattoos. Police said he confessed to the shootings, but did not offer further evidence against him.

Castillo says La Familia has been trying to expand into Mexico City from its stronghold in the Pacific coast state of Michoacan. The capital has been largely spared from the massacres, beheadings and other cartel-style violence gripping some parts of Mexico.

The cartel, known for bold attacks on security forces and indoctrinating gang members in pseudo-Christian ideology, was one of the first targets of President Felipe Calderon's intensified war against drug traffickers.

Calderon sent thousands of troops into Michoacan, his home state, in late 2006 shortly after La Familia announced its emergence by rolling five severed heads into a nightclub in the town of Uruapan.

Several of its top members have been brought down in recent months, including leader Nazario Moreno, who was killed in a December gunbattle with police.

The government contends La Familia is in retreat, and banners appeared around Michoacan last month claiming La Familia had dissolved itself. However, Michoacan state lawmakers dismissed the messages as a ploy to distract attention from the cartel.

Castillo said the first shooting in the Iztapalapa neighborhood targeted rival drug dealers. The other two, which occurred in Nezahualcoyotl, were against members of Vasconcelos' own gang whom he feared had betrayed him, Castillo said.

Castillo said La Familia appears to be encroaching in eastern Mexico state while a new gang known as "La Mano Con Ojos" -- "The Hand With Eyes" in English -- has established itself in the western part.

Castillo said the new gang is believed to have split off from the Beltran Leyva cartel, which has been reeling since the death or capture of most of its leaders over the past year.

The Beltran Leyvas largely controlled drug trafficking routes in three states south of Mexico City, including Guerrero, home to the resort city of Acapulco, where the remnants of the gang are believed to be fighting. Two bodies were found Thursday in Acapulco, one inside a bullet-ridden car and another blindfolded with his hands tied, state police said.

In northern Mexico, meanwhile, an 11-year-old boy and his father were killed when gunmen ambushed their car in the border city of Ciudad Juarez, state prosecutors' spokesman Arturo Sandoval said Thursday.

The gunmen first opened fire on the car, then set it on fire. The boy's body was found inside the car while his father died on the pavement.

Also in Ciudad Juarez, assailants burned the house of social activist Malu Garcia, the latest attack on activists in one of the world's most dangerous cities.

Garcia said her house was burned while she was at a protest with Marisela Reyes, sister of Josefina Reyes, another activist who was killed in January 2010. Josefina Reyes had led protests against alleged abuses by Mexican soldiers in the Juarez valley.

Garcia had been protesting to demand that results into an investigation into the disappearance last week of three relatives of the Reyes sisters. Last week, the assailants also torched the house of Reyes' mother.

More than 3,000 people were killed last year in the city across the border from El Paso, Texas, violence largely blamed on a turf war between the Juarez and Sinaloa cartels.

Nationwide, nearly 35,000 people have been killed in drug-gang violence since Calderon deployed troops and federal police four years ago to crush the cartels in their strongholds.