MEXICO CITY (Reuters) - Mexican police officers are among the suspects under investigation in the killing on Wednesday of a son of the former chairman of the country's most powerful political party.
Homero Ramos, attorney general of the state of Coahuila, said on Friday seven people had been arrested in connection with the killing of Jose Eduardo Moreira, son of Humberto Moreira, ex-chairman of the Institutional Revolutionary Party, or PRI.
Ramos told Mexican radio that local officials appeared to be involved in the murder, among them police officers.
"First of all, there's evidence that some municipal police participated ... in what happened," he said.
Mexican police are frequently implicated in serious crimes as they are often in the employ of cash-rich drug cartels. Local police can earn as little as 7,000 pesos ($550) a month.
Mexico's political establishment was stunned by the killing of Jose Eduardo Moreira, a member of one of the best-known political families in the PRI, a party that ruled Mexico from 1929 to 2000.
The PRI will return to power when Enrique Pena Nieto assumes the presidency on December 1.
The body of Moreira was found near Ciudad Acuna, a city just south of the U.S. border renowned as a crossing point for drug traffickers.
According to some media reports, the Zetas cartel carried out the murder in revenge for the killing of a relative of senior gang member Miguel Trevino by security forces in Coahuila this week. Ramos said that was one possible explanation.
Humberto Moreira governed Coahuila before he became PRI chairman and his brother Ruben is now state governor.
On Thursday, Moreira described his son, who worked for the state government, as a victim of the criminal violence plaguing Mexico, but did not offer more details.
More than 60,000 people have been killed in violence related to the drug gangs since President Felipe Calderon took office six years ago and launched a military offensive against the cartels.
Humberto Moreira, who was a critic of Calderon's handling of the cartel violence, stepped down as PRI chairman last December after a scandal surrounding his management of Coahuila's finances. The state's debt ballooned under his watch.
(Reporting By Dave Graham; Editing by Peter Cooney)