The family of murdered Border Patrol Agent Brian Terry wants justice, and that may include suing the federal government.

"If the evidence shows Brian's death was proximately caused by the negligence of the federal government, there may be a cause of action," said Terry family attorney Paul Charlton.

Terry was killed in December 2010 at the hands of an illegal immigrant working for the Sinaloa Cartel while patrolling an area near Tucson known as Rio Rico.

Officials traced the gun found at the scene to Operation Fast and Furious, a weapons trafficking program run by the U.S. Department of Justice and the Bureau of Alcohol, Tobacco, Firearms and Explosives that let guns travel south of the border.

Generally speaking, government officials can't be sued for damages, however misguided or incompetent. Yet, there are exceptions when agencies can reasonably foresee their actions will do harm.

While it's too premature to know who likely would be fingered in a suit, it is possible that top ATF and Department of Justice officials could be the targets.

Defendants successfully sued the FBI three times when their informants committed murder. The U.S. government was made to pay millions of dollars to the victims families after it was found that federal agent created an unreasonable risk of harm to them by helping the informants avoid arrest. The IRS was also sued for close to $1 million when it failed to supervise one of their informants who also committed murder.

According to Charlton, the Terry family says it doesn't want U.S. officials prosecuted criminally, but civil court is something else.

"Anyone who put these weapons in the killers' hands may be liable," he said.

Charlton was Arizona's U.S. Attorney for 7 years. He understands the ATF and the internal chain of command on an operation the size of Fast and Furious.

"I have never seen an investigation in which guns were intentionally allowed to walk. That sort of thing does not happen, ought not to happen," he said.

Charlton says a decision on future legal action will depend on the evidence. Congressman Darrell Issa, chair of the House Oversight & Government Reform Committee, initiated hearings on the Hill after learning the ATF helped sell thousands of guns to known criminals.

His hearings opened a floodgate of evidence against the agency, and provided a forum for whistleblower agents to air their concerns, which included multiple warnings to supervisors that the program was going to kill people.

Those warnings were ignored, despite reports showing Mexican police were recovering Fast and Furious guns at crime scenes throughout that country.

"Brian Terry's loss was preventable," said Issa. "It was regrettable and preventable."