The Justice Department has not said whether it will seek the death penalty against Loughner, the suspect in the shooting of Rep. Gabrielle Giffords and the deaths of a federal judge, a congressional aide and four other people. But federal prosecutors already are moving forward with charges, and veteran lawyers anticipate they will ask for him to be executed.
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Many witnesses and ample evidence strongly suggest the government will have no trouble placing the gun in Loughner's hands at the Tucson shopping center where the shootings took place. Internet postings and material investigators said they found at Loughner's home suggest that he had prior contact with Giffords and might have been planning something along the lines of Saturday's rampage.
Yet comments from friends and former classmates bolstered by Loughner's own Internet postings also have painted a picture of a social outcast with almost indecipherable beliefs steeped in mistrust and paranoia.
On Monday, Loughner made a brief appearance in court, where he acknowledged the charges against him and was ordered held without bail.
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Before the attempted assassination of Reagan, Harvard Law School professor Alan Dershowitz said in a telephone interview Monday, "this would be a clear case of insanity, because the pre-meditation would not be seen as undercutting insanity, it would be part of demonstrating insanity." But under the post-Hinckley rules, he said, "that's a very uphill battle."
Public outrage over the jury's verdict in Hinckley's trial - not guilty by reason of insanity - prompted Congress to make it much more difficult to establish that claim in federal criminal trials.
Arizona also has modified the insanity defense so that a defendant in a state trial no longer can be found not guilty by reason of insanity. Instead, the jury can deliver a verdict of guilty but insane, said Pima County Attorney Barbara LaWall. "So the person is held at a state mental hospital, and if sanity somehow comes back, he's transferred to prison, not just let go," LaWall said.
The case against Loughner is at an early stage, as is his defense.
His lawyers probably will spend their time making the strongest possible argument to dissuade prosecutors from pursuing the death penalty. "That's the task of his lawyer in the first instance," said Neal Sonnett, a Miami defense lawyer.
Among arguments that could be made is that, if not insane, Loughner was mentally impaired. That argument concedes that a defendant bears some responsibility for what he has done but lacks the guilt necessary to face the death penalty. The compromised state of mind sometimes is referred to as "diminished capacity."
Dershowitz predicted that federal officials will seek death for Loughner no matter what his lawyers argue. "The prosecution will seek the maximum punishment in a case like this," he said.
A veteran of death cases, San Diego attorney Judy Clarke, led the team that represented Loughner at his court appearance Monday. Clarke succeeded in negotiating a guilty plea and a life sentence for the Unabomber, Theodore Kaczynski. She also helped spare the life of serial bomber Eric Rudolph and Susan Smith, convicted of drowning her two little boys.
Only Oklahoma City bomber Timothy McVeigh and two others have been executed in the federal system since the federal death penalty was reinstituted in 1988. Sixty other inmates are under federal death sentences, according to the Death Penalty Information Center.
If there is a trial and guilty verdict, discussion of Loughner's mental state will again be a factor in a separate court hearing before the jury deliberates over a sentence.
Even if Loughner were to avoid a federal death sentence, he still could face state murder charges that carry with them the possibility of execution, lawyers said.
"It's often the case that both jurisdictions would file charges and then sort it out later," said John Canby of Phoenix, a board member of the state association of criminal defense lawyers. "If for some reason, the feds didn't want to go for the death penalty or didn't get it, it would be available at the state level perhaps."
Loughner is charged with one federal count of attempted assassination of a member of Congress, two counts of killing an employee of the federal government and two counts of attempting to kill a federal employee.
LaWall said her office would handle all the other charges against Loughner, including for four deaths of people who were not federal employees, more than a dozen wounded and dozens more who were in the line of fire but not injured. Her staff is researching whether state charges have to wait until the federal prosecution is complete.
"If it takes two years to prosecute in the federal system, I don't want to make all these witnesses and victims wait," she said.
LaWall said the lead prosecutor from her office on the case has handled dozens of capital trials and that a team of prosecutors would weigh whether to seek the death penalty. She said at least two factors were present in favor of it - and, with the death of 9-year-old Christina Taylor Green, a victim under the age of 15.