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There may be traitors and spies in our midst but don't count on them getting charged with treason.

Several members of the U.S. military and regular U.S. citizens have faced — or are facing — serious charges of crimes committed against their country. The latest case came Thursday when Susan Lindauer, a Maryland woman, was charged with being a spy for Iraq.

And although many Americans may like to see more traitors put to death — particularly since the Sept. 11, 2001, terrorist attacks — legal experts say it's not that easy.

"I don't think there's any hesitancy about using it [death penalty as punishment] in the federal system, the military or the military tribunals but these cases are not actually that easy to make," said Richard Dieter, executive director of the Death Penalty Information Center (search).

"The crimes are high level but the proofs are much harder to come by in terms of witnesses, cooperation … it's much more important to find out how there was a hole in the protection against spying rather than to maybe get an execution some years down the road."

Killing a fellow soldier or citizen in wartime, however, is an easier crime to slap with the death penalty, experts said.

Sgt. Hasan Akbar (search) is facing the prospect of the death penalty on murder and attempted murder charges for throwing grenades into the tent of 101st Airborne Division soldiers in Kuwait last year, killing two officers and injuring 14 others. It's the first time since the Vietnam War a U.S. Army soldier is being prosecuted for the murder of another soldier during wartime.

"That's a lot easier than trying to figure out treason … if I just kill another soldier, why is that on behalf of another power?" asked Leon Friedman, law professor at Hofstra Law School (search). "In order to have treason, you have to conspire and aid the enemy."

All of the seven men now on the military's Death Row at Fort Leavenworth (search) in Kansas are convicted murderers.

In other cases, where the loyalty of a military person or another U.S. citizen is questioned, seeking the death penalty is often a last resort.

Lindauer, a former journalist and congressional press secretary, faces up to 10 years in prison for allegedly providing information to Iraq. On Thursday, she proclaimed her innocence and said she was simply an anti-war activist.

But National Guardsman Spc. Ryan G. Anderson (search) faces the death penalty for aiding the enemy after being accused of turning over U.S. Army information and means of killing military personnel to Al Qaeda.

An Army spokesman at Ft. Lewis, Wash. — where Anderson was based — said an Article 32 investigation surrounding Anderson is ongoing, and "I can't speculate on them, on possibilities or charges" that may include the death penalty. An Article 32 hearing (search) is the military equivalent of a pretrial hearing, and will determine whether a suspect faces a court-martial.

Treason, the only crime specifically defined in the U.S. Constitution, consists of levying war against the United States, "adhering" to its enemies and "giving them aid and comfort." A person cannot be convicted of treason unless two witnesses testify to the act, or the suspect confesses.

"The case that got people thinking about treason was the case of John Walker Lindh (search) … and there was nothing there," said Eugene Fidell, a lawyer with Feldesman Tucker Leifer Fidell. "Prosecuting people for treason … you really have to be in the government's face in a very, very direct and annoying way.

"It's hard to prove because of the extraordinary stigma attached to it. We don't like to prosecute people for treason," Fidell said.

John Walker Lindh — a.k.a. "Taliban John" — was sentenced to 20 years in prison after he pleaded guilty to one count of supplying services to the Taliban carrying a rifle and hand grenades while fighting against the U.S.-backed Northern Alliance (search).

As part of the plea deal, the government dropped all other counts against the Californian, including conspiracy to kill CIA officer Johnny Michael Spann (search).

Experts said so-called traitors can be charged with a myriad of other crimes, such as supplying material to terrorist organizations, since it's doubtful treason cases will come to fruition.

"We don't have treason trials — it's a very clumsy mechanism for trying to deal with terrorists or bad guys or even American citizens trying to do bad things," Friedman said. "There's just too many barriers for that kind of conviction."

Government prosecutors say retired Air Force Sgt. Brian Patrick Regan (search) was willing to sell out his country by spying for Iraq, Libya and China for $13 million. His trial is still ongoing. That's the first espionage case in 50 years that could lead to the death penalty.

Former FBI agent Robert Hanssen (search) spent 20 years selling U.S. secrets to Moscow in return for more than $1.4 million in cash and diamonds. He was indicted on 21 espionage-related counts, most of which carried a maximum sentence of death. In July 2001, he pled guilty to 13 counts of espionage in exchange for a life sentence.

Some Americans think that of all the traitorous people to be made an example of for turning against their country, Hanssen is one that should have been it.

"What bothers me is to see people like Robert Hanssen ... get spared from execution," said Peter Murphy, an education consultant. "These individuals should have been made an example of and gotten a firing squad to send the message to those on the inside who are tempted by greed to betray their country."

But others think the death penalty should be a last resort, even for supposed turncoats in the war on terror.

"Executing people because they are suspected of terrorist activity or feeding secrets to foreign regimes on speculation alone is [a] dangerously slippery slope," said Claire Greenspan, a publicist in New York City. "You can set someone free after proving they have been unjustly accused — you cannot bring them back to life."