The federal prosecutor who put two border agents behind bars was unapologetic Tuesday about his handling of the case before his Senate inquisitors.

"When lawmen break the law, we must hold them to account," said Johnny Sutton, U.S. Attorney for the Western District of Texas.

Former border agents Ignacio Ramos and Jose Compean remain in federal prison while their case is under appeal. They were convicted by jury in March 2006 for the non-fatal shooting in the buttocks of a Mexican drug runner, Osvaldo Aldrete Davila. Ramos and Compean were convicted of violating federal gun laws and attempting to cover up the shooting. The two are serving 11- and 12-year prison sentences.

"Their actions after the shooting show that they knew that the shooting was illegal and destroyed the credibility of their later claims that the drug smuggler appeared to have a weapon and ran away," Sutton said.

"To excuse their crimes they have since claimed that they were only doing their jobs. But the job of a United States border patrol agent is to protect the American people and to enforce the laws of our country, not commit crimes such as assault, obstruction of justice and violation of civil rights," Sutton added.

Heavy mandatory prison sentences and a prosecutor's actions were in the crosshairs Tuesday as the Senate subpanel began quizzing witnesses Tuesday in the complicated case.

Border Patrol agents should be allowed to shoot at fleeing drug traffickers, a Republican senator suggested Tuesday.

"Why is it wrong to shoot the (trafficker) after he's been told to stop?" asked Sen. Tom Coburn, R-Okla.

A number of people have lined up on Ramos and Compean's side, however, including Reps. Duncan Hunter and Dana Rohrabacher, both California Republicans. The two lawmakers testified on their behalf Tuesday before the Terrorism, Technology and Homeland Security subcommittee of the Senate Judiciary Committee.

The facts of the case "comprise to me the most severe injustice I've ever seen with respect to the treatment of U.S. Border Patrol agents, or, I might add, the treatment of any uniformed officers," said Hunter, the first witness to speak before the panel.

Rohrabacher accused Sutton for overreaching with his investigation, saying that Ramos and Compean's biggest mistake — not writing up their shooting incident — was not deserving of their punishment, which set them in prison. Later, Ramos suffered a prison attack and the two are now in solitary confinement.

"That decision — that deserved a reprimand — was turned into a felony ... which should have been addressed at most with a five-day suspension," Rohrabacher said.

"The prosecutors decided to go after the good guys and give the bad guy immunity," Rohrabacher said.

It's not disputed whether Davila was bringing drugs into the country, but there still remains a dispute over whether the agents had reason to believe he was armed. Ramos and Compean's supporters also remain upset over prosecutors giving Davila immunity from prosecution for his testimony.

Ramos and Compean's supporters are seeking a presidential pardon on their behalf.

The Associated Press contributed to this report.