Juan Frayre Escobedo, the son of slain Mexican human rights activist Marisela Escobedo, said his mother was murdered by Antonio Barraza, brother of Sergio Barraza, who is accused of murdering Frayre Escobedo's sister, Rubi.

"My mother's killer is the brother of the man who murdered Rubi, and we have told the authorities again and again. We do not know why they prefer to present a scapegoat instead of arresting the real killer," Frayre Escobedo said in a press conference Wednesday in El Paso, Texas.

Marisela Escobedo was murdered on Dec. 16, 2010, in front of the Governor's Palace in Chihuahua city, the capital of the like-named northern Mexican state.

The Barraza brothers are members of Los Zetas, considered Mexico's most violent drug cartel, Frayre Escobedo said, adding that he was threatened by Antonio Barraza outside an El Paso shopping center.

Manuel Garcia, who is requesting political asylum in the United States, said in a separate press conference Wednesday that he fled Mexico because he was being pressured by the Chihuahua Attorney General's Office, which employed him as an informant, to say that Marisela Escobedo belonged to the Sinaloa cartel.

"They wanted to make my mother out to be a drug trafficker so they could get the pressure off to investigate her murder and have to prosecute an American, a member of the Los Zetas gang for her murder," Frayre Escobedo said.

Marisela Escobedo was gunned down after spending two years demanding justice for Rubi Marisol Freyre, who was only 16 when she was killed in 2008.

Escobedo was murdered while picketing in front of the Governor's Palace to demand that those who killed her daughter be prosecuted.

The human rights activist had staged numerous marches and other protests in Ciudad Juarez, located across the Rio Grande from El Paso, Texas, and in Chihuahua city, demanding that the governor ensure there was justice in her daughter's case.

The 52-year-old woman staged her protest in front of the Governor's Palace after learning that Sergio Barraza, Rubi's boyfriend and the main suspect in her killing, had moved to Zacatecas state after being acquitted at his first trial and joined Los Zetas, perhaps the most ruthless of Mexico's powerful drug cartels.

"I have always said that my mother became a problem for the authorities and that is why they allowed her murder right in front of their offices, where she had a little table asking for justice," Frayre Escobedo said.

Prosecutors identified a 29-year-old man earlier this month as Escobedo's killer.

Jose Enrique Jimenez Zavala was arrested on Oct. 4 in a shopping center parking lot while accompanied by his wife, two children and another individual, the Chihuahua Attorney General's Office said.

Jimenez Zavala also allegedly participated in the massacre of 16 people at the El Colorado bar in April, the AG's office said.

Ricardo Escobedo, Marisela's brother and a witness to her murder, disputed prosecutors' claims, saying that Jimenez Zavala was not the gunman.

Frayre Escobedo and five other members of his family are in El Paso, located across the Rio Grande from Ciudad Juarez, where they fled after receiving death threats in Mexico.

"Nothing is going to bring back my mother, but we do not want her death to go unpunished," Frayre Escobedo said. EFE