He was described, in the immediate aftermath of the , as a cheerful and careful pilot, a young man who had dreamed of flying since boyhood.
But in the days since, it has seemed increasingly clear that Andreas Lubitz, 27, the plane’s co-pilot, was something far more sinister: the perpetrator of one of the worst mass murder-suicides in history.
If what researchers have learned about such crimes is any indication, this notoriety may have been just what Mr. Lubitz wanted.
The actions now attributed to Mr. Lubitz — taking 149 unsuspecting people with him to a horrifying death — seem in some ways unfathomable, and his full motives may never be fully understood. But studies over the last decades have begun to piece together characteristics that many who carry out such violence seem to share, among them a towering narcissism, a strong sense of grievance and a desire for infamy.
Adam Lankford, an associate professor of criminal justice at the University of Alabama, said that in his research on mass killers who also took their own lives, he has found “a significant number of cases where they mention a desire for fame, glory or attention as a motive.”
Before , 20, the , killed 20 children, six adults and himself in 2012, he wrote in an online forum, “Just look at how many fans you can find for all different types of mass murderers.”
Robert Hawkins, 19, who committed suicide after killing eight people at a shopping mall in Omaha in 2007, left a note saying “I’m gonna be famous,” punctuating the sentence with an expletive.
And , 17, of Columbine High School fame, bragged that the goal was to cause “the most deaths in U.S. history…we’re hoping. We’re hoping.”
“Directors will be fighting over this story,” Mr. Klebold said in a video made before the massacre.
If authorities know what might have driven Mr. Lubitz, they have not made it public. Prosecutors said last week that it was now clear that he , researching ways to commit suicide and how to operate the cockpit door on his iPad.
Lufthansa, Germanwings’s parent airline, has said that Mr. Lubitz had reported and prosecutors have said he had talked to a counselor about suicide.
Yet mental health experts who study mass murder-suicides said that depression and thoughts of suicide, which are commonplace, fall far short of explaining such drastic and statistically rare acts.
“People want an easily graspable handle to help understand this, to blame something or scapegoat,” said Dr. James L. Knoll, the director of forensic psychiatry at the State University of New York Upstate Medical University.
But to zero in on depression is “a low-yield dead end,” he said, adding, “There’s something fundamentally different here, aside and apart from the depression, and that’s where we need to look.”
Serious mental illness, studies of mass killers suggest, is a prime driver in a minority of cases — about 20 percent, according to estimates by several experts. Far more common are distortions of personality — excesses of rage, paranoia, grandiosity, thirst for vengeance or pathological narcissism and callousness.
“The typical personality attribute in mass murderers is one of paranoid traits plus massive disgruntlement,” said Dr. Michael Stone, a forensic psychiatrist in New York who recently completed a study of 228 mass killers, many of whom also killed themselves.
“They want to die, but to bring many others down with them, whether co-workers, bosses, family members or just plain folk who are in the vicinity.”
Mr. Lubitz, Dr. Stone noted, now ranks among the deadliest of mass killers, in a league with Adilson Marcelino Alves, who in 1961 killed as many as 500 people in a circus fire in Brazil, or , the Oklahoma City bomber, who killed 168 people and injured more than 680 others.
Dr. J. Reid Meloy, a forensic psychologist who consults on threat assessment for universities and corporations, said perhaps the most salient feature of mass killers was their belief that they had been wronged.
“What’s become clear over the past 30 years of research is that there’s virtually always a personal grievance that will start a person on a pathway to mass murder,” Dr. Meloy said.
The target of the grievance, he said, could be a person, a company, an institution or a government, “but it is felt personally and typically involves a major loss or anticipated loss.”
In Mr. Lubitz’s case, whether he knew or cared who would die as result of his actions remains unclear.
“For some people, the targets are very much the purpose of the attack,” Dr. Meloy said, referring to mass killers. “I think for other cases, where the purpose of the attack is, for example, primarily to gain notoriety, then the targets in a sense become the means to that end. One could think of them as being collateral damage.”
Murder-suicides make up only a small percentage of homicides in the United States, accounting for about 1,000 to 1,500 deaths a year, according to a 1992 epidemiological study. The vast majority are committed by men and most are domestic violence cases: an estranged husband, for example, who kills his wife, girlfriend or lover.
Suicides accompanied by the killing of multiple strangers represent an even tinier fraction of homicides over all. But they seem to differ in significant ways from their domestic counterparts, researchers said.
In domestic cases, depression does appear to play a significant role. A recent psychological autopsy study of murder-suicides in Dallas, most of which involved domestic violence, found that 17 of the 18 perpetrators met the diagnostic criteria for major depression or some other form of the illness.
The study, conducted by Dr. Knoll and Dr. Susan Hatters Friedman, a forensic psychiatrist at Case Western, found that a majority of the killers also abused alcohol or drugs. Four had a family history of suicide. The study has been submitted to a scientific journal.
Domestic murder-suicides are almost always impulsive — committed in fits of rage or jealousy, often enabled by the presence of a firearm. In contrast, killers who take groups of strangers as targets plan their crimes carefully, waiting for an opportunity to act.
And while domestic murder-suicides are frequently fueled by alcohol, people who plan ahead to kill themselves and others seem concerned about keeping a clear mind for the task ahead.
George Sodini, 48, who killed three people and injured nine others at an aerobics class in a Pittsburgh suburb in 2009, said as much in a blog he kept, detailing his plans.
“I haven’t had a drink since Friday at about 2:30,” he wrote on Monday, Aug. 3, the day before the massacre. “Total effort needed. Tomorrow is the big day.”
An airplane may seem an unusual vehicle for mass murder or self-destruction. But as a pilot’s method of choice, several psychiatrists said, it is perhaps not that surprising.
In a study of 85 aircraft suicides from 1965 to the present, Dr. Hatters Friedman and Dr. Chris Kenedi, a psychiatrist at Duke, found that 18 of the crashes appeared to be murder-suicides, 15 perpetrated by pilots. The study looked at general aviation and commercial airline crashes, and included the deliberate crashes by pilots of a Mozambique Airlines jet in 2013 and an EgyptAir plane in 1999.
was not among those studied, although pilot suicide was one theory about the jetliner’s disappearance last year.
“Not all of them had a history of mental illness,” Dr. Hatters Friedman said of the pilots. “What keeps coming up is family stresses, relationship stress, work stresses, financial stresses.”
In several cases, the pilots, all men, seemed to be acting on grievances. One crashed a plane into his former mother-in-law’s house, another into the offices of the pilot’s employer. A third pilot flew a Piper Dakota into a building occupied by the Internal Revenue Service.
Yet few murder-suicides are as chilling as those involving the deliberate crashing of jetliners with hundreds of passengers aboard.
In a mall or in a school, Dr. Knoll noted, people can run and take cover.
“On a plane, your number of victims is set,” he said, “and nobody can go anywhere.”
A news analysis article on Tuesday about research into the characteristics of mass killers who also take their own lives misstated the source of a statement about the mental health of Andreas Lubitz, the pilot of a Germanwings jet who killed himself and 149 others in the French Alps last month. Prosecutors — not Lufthansa, Germanwings’s parent airline — said he had talked to a counselor about suicide.