(Recasts, adds comment from Border Patrol agents' union)

BISBEE, Ariz., Aug 6 (Reuters) - A U.S. Border Patrol agent must stand trial for murder in the shooting of a Mexican man trying to enter the United States, an Arizona judge ruled Monday in a case that drew criticism from Mexico.

Agent Nicholas Corbett was charged in April with four counts of homicide in the Jan. 12 shooting of Francisco Dominguez Rivera shortly after he crossed the border illegally on a stretch of desert between Douglas and Naco.

Cochise County Justice of the Peace David Morales ruled the evidence supported lesser charges of second-degree murder, but threw out charges of first-degree murder, which supposes premeditation.

The ruling followed a preliminary hearing that heard evidence from three illegal immigrants present at the shooting, a pathologist, county sheriff's detectives and two Border Patrol supervisors.

No date was set for Corbett's arraignment.

Following the killing, Mexico's Foreign Ministry complained of "disproportionate violence" and instructed the Mexican Embassy in Washington to investigate the circumstances.

Last year, border police captured 1.1 million undocumented immigrants crossing over the border from Mexico and recorded a soaring number of attacks on agents.

Lawyers for Corbett argue he shot Dominguez Rivera in self-defense after he was threatened with a rock.

An agent representing the local chapter of the Border Patrol's union said he believed the charges against Corbett would not hold up at trial.

"I don't think the prosecution has a good case, and the defense will absolutely beat it," Brandon Judd said after the hearing.

Last year, two Border Patrol agents were prosecuted in Texas for shooting an unarmed Mexican drug smuggler in the buttocks.

They were convicted and sentenced to more than 10 years in jail, becoming a cause celebre among some conservatives and anti-illegal immigration hard-liners.

AlertNet news is provided by