The mother of José Antonio Elena Rodriguez—a 16-year-old Mexico native who was killed by a Border Patrol agent three years ago during a cross-border shooting—says it was difficult to see the agent's face in court this morning and not be able to scream at him.

The agent, Lonnie Swartz, attended his arraignment hearing this morning at the Evo A. DeConcini U.S. District Court, where he was formally advised of the charges against him and pleaded not guilty to second-degree murder.

Swartz was free to go without paying a bond, and he's under pre-trial rules, which include handing over all weapons in his possession, checking in with his pre-trial officer, turning in travel documents, and attending all future hearings. 

"You wouldn't understand how I feel as a mother," Rodriguez said in Spanish. She briefly spoke to the media after leaving the hearing. "It is very difficult to be in court, watching the murderer of my son, and not be able to tell him anything, without being able to scream at him. I thank all of you for being with us through every step of this process."

Swartz was charged with second-degree murder last month for shooting across the border into Nogales, México and killing Elena Rodriguez on Oct. 10, 2012.

Witnesses of the shooting say Elena Rodriguez was walking home on the Nogales, Sonora side of the fence, when he was hit by 10 bullets. Border Patrol agents allege rocks were being thrown at them, which triggered the shooting. 

Border Patrol spokesman Art del Cueto says events like this shouldn't divide people into pro or anti-Border Patrol groups. The animosity against border agents makes others forget about the great dangers they face while on the job, he said.

"We believe in our job, we are just trying to get home to our families," del Cueto told the press before the hearing. "There are tons of rockings agents go through (that are) unreported, attacks ... that go unreported. When we have the division, people don't understand the dangers...things like this happen...indictments, shootings and killings, but the agent still wakes up every morning, puts on that uniform and does the same job every day.

Swartz's trial was tentatively scheduled for Nov. 17.