Husbands kill their wives more often than wives slay their husbands, and parents are twice as likely to murder their children than the reverse, according to a Justice Department study released Sunday.

"Murder in Families" was based on more than 8,000 homicides in large urban counties where at least one murder defendant in the case went before a court in 1988.The study found that 16 percent of murder victims, 1,308 people, were members of the defendant's family. Of the remainder, 64 percent were murdered by someone they knew and 20 percent by strangers.

Husbands and wives were the family members most likely to be involved in family murders; they were victims or defendants in 41 percent of the cases, according to the study by the department's Bureau of Justice Statistics.

When spouse murdered spouse, the husband was the assailant in almost two-thirds of the cases, the survey revealed. However, among black couples, wives killed their husbands at about the same rate as husbands killed wives - 47 percent of black spouse victims were husbands and 53 percent were wives.

Patrick Langan, one of the study's researchers, said he could not explain why black husbands and wives killed each other at virtually the same rate. He said it was one of several unexpected trends uncovered by the study.

"What surprised me most was not that many of the people who commit murder have a prior criminal record; it was that over half the murder victims themselves had a criminal record," he said in an interview.

He also said he did not expect to discover that parents kill their children as often as they do. It was the second most frequent type of family murder, accounting for 21 percent of the family murder cases.

"I would have thought that such a bizarre event would have been the least frequent type of murder," he said.

This also was the only family murder category where women were the killers more often than men.

Most murders inside the family tended to happen at night and in the home, the researchers found. About 48 percent of defendants in family murders had been drinking around the time of the crime, while one-third of the family murder victims had drunk alcohol.

When a mother killed her child, she was more likely to murder a son than a daughter: 64 percent killed sons, while 36 percent killed daughters, the study found.

But when a father killed his child, he was more likely to kill a daughter than a son: 52 percent daughters vs. 48 percent sons.

Sons were almost as likely to kill their mothers as their fathers. But when a daughter killed a parent, her victim was her father in 81 percent of the cases.

The study challenged the common criticism that the justice system treats family violence less seriously than violence among strangers or acquaintances.

"In several important respects, the criminal justice outcomes of family murder defendants were about the same overall as those of other murder defendants," the researchers wrote.

For example, family murder defendants were just as likely to be charged with first-degree murder; they were no more likely to have their cases diverted or dismissed or to be acquitted; and they were as likely to have their cases result in a conviction for some crime.

A little more than half the defendants in family murders had been arrested in the past, compared with almost 77 percent of defendants in non-family killings. Yet convicted family murder defendants were as likely to receive a prison sentence as convicted non-family defendants - 88 percent and 91 percent, respectively.

Firearms were used in 42 percent of family murders, less often than the 63 percent of all non-family murders, according to the study.

In murders of children under age 12, the victims' parents were the defendants 57 percent of the time. Seventy-nine percent of those youngsters had been previously abused by their assailant.

When the victims were age 60 or over, a son or daughter was the killer only 11 percent of the time.

The survey's information was drawn from prosecutors' records in the 75 largest counties and was based on a representative sample of all murder cases disposed of in 1988. The estimated 8,063 victims were killed in 1988 or earlier. For perspective, there were 20,860 murder victims in 1988, and an estimated 24,500 last year.