Michael Swanson reacted to his conviction for murder with a smile. He gave a double middle-finger salute in the courthouse. "I'm good," he said after learning he'd be in prison the rest of his life for killing an Iowa store clerk.

Those actions, and others, by the 18-year-old from St. Louis Park may seem far from sane. Yet it took an Iowa jury less than an hour Thursday to reject his attorney's insanity defense, a strategy that Twin Cities lawyers said is rarely used and almost never works.

"You'd have to shoot somebody but actually think you were eating a carrot and then convince a jury of that," said Minneapolis attorney Joe Friedberg, who says it's been 33 years since he last won a jury verdict using a mental-illness defense.

"Winning with a mental-illness defense is virtually impossible," Friedberg said. "You've got to show there's a diagnosed major mental illness for which there is treatment. Psychopaths and personality disorders don't qualify. There's no cure for them."

In April, an Eden Prairie man who had drowned his baby in a laundry tub was found not guilty by reason of mental illness. In that case, the reports of three psychiatrists, a well-documented history of the defendant taking a leave from his job because of mental-health problems and an agreement between prosecutors and the defense convinced Hennepin County Judge Mark Wernick that Randel Richardson, 37, "was laboring under such defective reasoning."

Juries are a tough sell

Convincing a jury that a defendant is mentally ill may be even more difficult than convincing a judge, Friedberg said. In 1978, he defended June Mikulanec, who had been accused of stabbing a woman more than 90 times. A jury found Mikulanec not guilty by reason of mental illness. It was the last time that Friedberg can recall winning a jury trial using a mental-illness defense.

"Jurors think of their personal safety. If the jury has a personal fear of the defendant, there's a better likelihood of selling a mental-illness defense," Friedberg said.

"But I don't think the kid in Iowa was mentally ill. His mother may think that, but I don't recall a psychiatrist testifying on his behalf."

In November, Swanson, then 17, shot convenience store clerk Sheila Myers in the face, killing her. His attorney, Charles Kenville, argued that Swanson was insane and did not know right from wrong when he shot and killed her at the store in Humboldt, Iowa.

Kathleen Swanson, Swanson's mother and the defense's lone witness, told of 18 years of attempts at getting her son help and how she often lived in fear of him.

But this was a jury trial, and jurors often want to hold somebody accountable, said Frederick Goetz, the former president of the Minnesota Association of Criminal Defense Lawyers.

"An insanity or mentally-ill defense is rarely used because most of the public don't really believe people are crazy," said Dr. Carl Malmquist, considered the dean of Twin Cities forensic psychiatrists by several of the lawyers interviewed for this article. "They assume everybody is normal, no matter how crazy a person acts."

Lawyers are reluctant to use a mental-illness defense because it shifts the burden of proof to the defense, said Malmquist, who has testified at more than 500 homicide cases and teaches at the University of Minnesota and William Mitchell College of Law.

Hinckley case fallout

Convincing a jury of mental illness became increasingly difficult 30 years ago, after John Hinckley's attempted assassination of President Ronald Reagan. Hinckley, who said he was trying to impress actress Jodie Foster, was found not guilty by reason of insanity.

"There was such a public outcry," said Dr. William Orr, a forensic psychiatrist based in Mendota Heights. Orr, an associate professor at the University of Minnesota and adjunct professor at William Mitchell College of Law, said that case upped the ante for what were already stringent criteria for insanity.

"To understand the mental status when someone committed a crime, we need records, records, records," Orr said. "You need records that show a person was so ill, they didn't know a chair from a door."

"There is also the perception, though untrue, that somebody who is found not guilty by reason of insanity has gotten away with a crime," said Minneapolis attorney Paul Engh, who said he partnered with Friedberg in a case in which they used a mental-illness defense, unsuccessfully.

In fact, most defendants who are found not guilty due to mental illness spend more time in controlled facilities -- state hospitals, usually -- than do people considered sane who are convicted of the same crimes, Orr said.

Orr would like to see Minnesota and other states adopt a new verdict: "guilty by reason of insanity."

"They did commit the crime," he said. "But they were also insane."

Ron Meshbesher, often called the dean of the Twin Cities defense attorneys, said that Swanson's securing a gun, driving to Iowa with a plan and telling a friend about it show that the teenager did contemplate what he was about to do.

Swanson will also stand trial next month in the shooting death of Vicky Bowman-Hall, 42, in Algona, Iowa, the same night.

"Did he know right from wrong? That's the test," Meshbesher said.

"I've used the insanity defense a couple of times, for murders," Meshbesher said. "But even when the defendant says he's hearing voices, or God told him to do this, it's still a last-ditch defense."

Paul Levy • 612-673-4419