When Fathers Kill : They’re depressed, alone. They feel financially strapped. And, increasingly, a warped sense of family values pushes them over the edge.

Other fathers have used knives, axes, guns, carbon monoxide, even fire.

But when Mark A. Clark, a laborer from Maryland, killed himself, his estranged wife, their daughter and her two other children last week, he chose a popular symbol of family togetherness--a station wagon.

Baltimore County police said Clark, 32, pretended he was going to take the children back-to-school shopping in his car, which contained a commercially available explosive. He drove behind a shopping center, where the device was detonated in a massive explosion that spewed body and car parts over buildings and trees.

The next day, a relative received a letter from Clark explaining that he was planning to destroy his family because he was distraught since he and his wife separated about six months ago.

Mental-health experts and sociologists are less bewildered at this perverse mix of family devotion and mass murderous rage than the general public, which, in an era of “family values,” tends to hold up the family as a sanctuary from violence or a cure for society’s many ills.

Nevertheless, family men have been killing their families, an act known as familicide, in relatively constant numbers throughout time. Experts say the number falls somewhere between 15 and 50 every year in the United States.

Dr. Park Dietz, a Newport Beach forensic psychiatrist, said, “Rather than family values being a protective force to prevent such events, it’s closer to being one of the causes of such events. These men have an over-idealized sense of family values.

“Honor is to the samurai who commits hara-kiri what family values are to the family annihilator,” said Dietz, who coined the term.

Although mothers sometimes kill themselves or their children, the so-called “family annihilators” are typically middle-aged, white fathers. Some are simply mercenaries intent on wiping out rival heirs or obtaining insurance money; a few have criminal backgrounds or histories of spousal abuse.

Richard Gelles, director of the Family Violence Research Program at the University of Rhode Island, said homicidal fathers come in two types: the overly enmeshed suicidal husband who can’t distinguish between himself and his family; and the controlling, angry man who is losing his grip on his family. After killings, acquaintances usually are shocked about the first type, saying something along the lines of, “He’s the last person in the world I would ever have suspected,” Gelles said. He is typically “very narcissistic and incredibly unhappy.”

Sociologist Jack Levin, author of “Overkill” (Plenum Press, 1994), said a significant number are angry, controlling men seeking revenge.

“More of these acts of family violence are premeditated,” said Levin, a professor of sociology and criminology at Northeastern University in Boston. “Traditionally, acts of family murder were not murder but manslaughter. It was impulsive, spontaneous.” Paralleling other crimes, family killings are increasingly committed with methodical planning, he said. “They really amount to an execution.

“We live in an age of rage,” Levin said. “A lot of this is economic. Many people feel their middle-class lifestyle is slipping away and they’re looking for someone to blame.”

The same day as the Clark killings, on the opposite side of the country, David Whitson, 35, shotgunned his estranged wife and three young daughters in Scotts Mills, Ore. He also wounded his mother-in-law, who was apparently holding his 6-month-old baby.

Whitson had reportedly been living alone for a year and had recently lost his job at Boeing. He was working for minimum wage at a rental-car agency. The subject of a restraining order for allegedly abusing his wife, he was also seeking primary custody of their children. Whitson’s lawyer said he was consumed with thoughts of reconciling with his family. He has been arraigned on murder charges.

Levin, who has studied scores of cases for his books on mass murder, said that just before killing, family annihilators have usually suffered a loss--either a separation or divorce or a job termination that makes them lose hope of ever being able to support a family. Even if the wives are the main breadwinners, husbands often still feel responsible, he said. They are banished from the family and living alone, and their angry thoughts can fester and intensify.

In that case, the husband may blame the wife and decide to kill all the children “to get even with her. They’re extensions of her,” he said. “She loves the children and so he wants to kill everything she loves in order to get even with her. In effect, he’s killing the family as a unit.”

On Father’s Day this year, a Simi Valley father, Larry Sasse, 31, shot and killed himself and his two children, ages 3 and 4. He was apparently despondent over the possibility of losing his wife, who had obtained a restraining order against him for alleged death threats. Last week, his widow, Debra, obtained a legal name change for herself and her two dead children. She said, “I don’t want any reference to their so-called father.”

In May, Leonardo Morita, a 46-year-old electrician, apparently planned to set fire to his San Marino house, killing his wife, three children and a housekeeper, in what authorities suspect was an effort to collect on insurance policies he had taken out on each family member other than himself. Authorities said he poured so much gas on the staircase to prevent his sleeping family from escaping that it leaked into the basement, igniting the water heater’s pilot flame and sparking an explosion. He died of his own injuries two months later before any charges were filed.

The largest family massacre in U.S. history was committed by R. Gene Simmons, 46, a retired U.S. Air Force master sergeant, who killed 14 family members plus two others at Christmas in 1987 in Russellville, Ark. “He waited at home for his relatives to arrive and over a period of 48 hours killed them one at a time,” Levin said. Simmons’ victims included his wife, children, two of the children’s spouses and four grandchildren.

Simmons, who had lost a part-time job in a convenience store, had been charged with incest and his wife had threatened to leave him. “His entire family decided they wanted nothing to do with him. In his eyes, they deserted him,” Levin said.

When Simmons was arrested, his eyes filled with tears and his lips quivered uncontrollably. He refused to talk about the killings, saying only that he wanted to die. In 1990, he was executed by lethal injection.

About 40% of family annihilators kill themselves; others are killed by police sharpshooters; others intend to kill themselves but can’t bring themselves to do it.

In 1989, a suicidal 28-year-old service manager for a tire store, Larry DeLisle, decided to drown himself, his wife and four children by driving their station wagon into the Detroit River in Wynadotte, Mich. But finding himself under 30 feet of water, he later said, his instinct was to save himself: “Your pilot mechanism says, ‘You can’t breathe. You are sucking water. Float [jerk]!’ ”

He and his wife extricated themselves, Levin recalls in “Overkill,” but the children, strapped into their car seats, died. Convicted of murder and attempted murder, he was sentenced to life without parole.

Said Dietz, who has examined six family annihilators as part of their prosecutions, the norm is not the enraged abuser who appears visibly dangerous, but a suicidally depressed man who has not sought treatment and has begun drinking heavily.

“You would find worse rap sheets for the average armed robber or burglar than you will for the average family annihilator,” Dietz said.

Dietz said family annihilators include attorneys, police officers and computer executives. Many were functioning well at work and were not under tremendous financial pressure at the time of the killings. “All said they were suicidal at the time, and all showed apparent anguish over what they had done. All indicated that they felt this was somehow going to be good for the family, or save the family, as opposed to the far more common motives for murder in which people say all kinds of things hostile about the victim.”

Suicidally depressed people develop tunnel vision regarding their options, he said. Rather than considering that a troubled marriage might lead to a new partner or a new life, family annihilators lock into ideas such as “the children would be better off with God than as orphans, or the idea that the family will be destitute and leaderless without me, or the idea that if my family won’t have me, no one else should have my family,” Dietz said.

Overvaluing the centrality of their role in their families, “The concept is: Without me, the family would be nothing.”

One of the most anguishing cases was that of 35-year-old Holliston, Mass., computer executive Kenneth Seguin, who two years ago axed his wife to death in bed, slit the throats of his two children and placed their bodies in water. After the killings, Seguin wounded himself with a knife. Although he drove away from the scene, he said that he meant to die, too. “Clearly the man was very sick and meant to take his children and family to heaven,” Dietz said.

But rather than being sent to a psychiatric institution, he was convicted of murder and sentenced to two consecutive life sentences because he admitted that he knew his actions were against the law and caused his children to suffer. In an emotional speech to the judge, he said, “I loved my wife and my children far too much to ever want to harm them in any way. They were my lifeblood. . . . Part of my soul died with my family.”

Sometimes family annihilators clearly announce their intentions to carry out their plans, but no one takes them seriously. Mark Clark had reportedly threatened to kill himself and his family two days before the blast. But according to a neighbor, “We all just thought he was blowing hot air.”

But many others do not issue loud and clear warnings, which makes such crimes nearly impossible to predict. Rather, they may show the subtle signs of depression that many relatives don’t recognize: increased drinking, sadness or irritability, social withdrawal, insomnia, a slowing of movements.

Said Dr. William Vicary, a Los Angeles forensic psychiatrist, “This guy is sinking and, typically, these people don’t reach out for any help, which makes it a more ominous situation.” If they do, they can often be helped by medications like Prozac and Zoloft, by cognitive psychotherapy or even electric convulsive therapy, Dietz said.

Sometimes they find other destructive outlets, and sometimes they get over it by themselves, Vicary said. “They work through it and life goes on, and nobody ever knows how close we came to some horrible situation.”