The snapshot is of poor quality. It shows a carefully laid out body, apparently a young woman's, dressed in clean, checkered cotton, with a lace-edged apron over her dress. Her glossy white skull seems to be grinning fiendishly. The flesh covering it was melted off with acid.

The photograph is in the files of the Salvadoran Human Rights Commission, part of a semmingly endless, sickening exhibit of beheaded, mutilated, tortured victims of human rights violations in this country.

Every day the commission members cull the newspapers -- for reports of corpses, announcements of kidnapings and disappearances, and obituaries. Every day, the relatives of victims file individual complaints, speaking haltingly over the phone or sitting on the edge of metal chairs before commission volunteers, talking of atrocities with chilling familiarity.

"It's been a year since they captured my husband," says one woman. "The police came in and took him away. We found him a week later, with a bullet through his head."

The new U.S. ambassador, Deane Hinton, noted in a recent interview that "it appears to be that a large part of the [human rights] problem comes from the lower ranks of the security forces."

The security forces here have been accused of acting as though they had unlimited man dates for fighting communism by any means. Human rights groups, journalists and others have documented numerous cases of civilian slaughter by the Salvadoran military in the name of fighting subversion.

But, like the spokesmen for the Salvadoran Christian Democrat-military coalition government, Hinton maintains that the situation is improving slowly. c

Violent and arbitrary death is only one problem Salvadorans face as a result of the ongoing civil war here. Unofficial suspension of human rights has been coupled with government suspension of most civil rights and freedom of information in what is described as a period of official "emergency."

Seven months ago the ruling civilian-military junta signed a decree regulating the treatment of suspects of treason, espionage, rebellion, sedition and other crimes against the security of the state. Decree 507 authorizes a military judge to detain a suspect incommunicado from 15 to 180 days and to sentence him to up to four months in corrective detention even if no proof has been found against him or her in the first six months of imprisonment.

There is sufficient cause to apply the Penal Code, Decree 507 states, if it is established that the accused belongs to organizations that have claimed responsibility for violations of the law. To establish that a suspect belongs to an organization, it is sufficient that this be confirmed by any national or international news medium.

One problem in establishing the rule of law is that in El Salvador, no one can be quite sure what the law is. The last constitution was carelessly drafted in 1966, but the proclamation of the junta that came to power Oct. 15, 1979, says the constitution will be enforced only when it does not contradict the spirit of the October 15 Movement's proclamation.

By virtue of a state of siege established a year and a half ago, all constitutional guarantees are suspended in any case. The state of siege must be renewed every 30 days, while existing martial law and a strict nightly curfew, put into effect in the days of the guerrillas' January offensive, have continued automatically. House-to-house searches by the armed forces during the curfew hours are common, and many of the dead on the Human Rights Commission's lists appear in the papers as curfew violators.

Other legal suspensions of civil rights are aimed more specifically at workers, apparently in an effort to prevent strikes and union activities in support of the guerrillas. Decree 43 placed the military in control of all vital public services. Decree 296 prohibits civil servants' right of association. Decree 544 suspends collective bargaining.

The last major strike took place in August, when the electricians' union -- which is sympathetic to the leftist guerrillas -- staged a three-day protest strike. The utility was taken over by the military and the union leaders were arrested. They are still awaiting sentencing.

The average Salvadoran has only a dim awareness of these events. Radio newscasts on national events, other than those boradcast by the government, are forbidden. In theory, censorship of the printed media does not exist, but there is little need for it. The last opposition newspaper, El Independiente, was shut down in January and several of its staffers are still in jail.

But it is the deaths, of course, that upset most people. The commission's charts show that violence peaked in May of last year, with 2,078 deaths. The number declined gradually through the second half of the year, leaped up again to 2,333 during January -- a figure that includes 500 guerrillas the government claims to have killed during that month's guerrilla offensive -- and dropped quickly after that to a relative low last May of 710.

The commission, and numerous other international human rights organizations, believe that these killings are largely the work of the security forces of the paramilitary groups they work closely with. The State Department, while it does not dispute the body count, does not agree that government forces are responsible for most of the deaths.

In a lengthy recent letter to Secretary of State Alexander M. Haig, Jr., Amnesty International said it had concluded, based on numerous sources of information including its own investigations, that "all branches of the Salvadoran security forces, whether nominally military, military police or paramilitary, have been implicated in human rights violations which have occurred on such a scale that they constitute a gross and consistent pattern of human rights abuses." Amnesty asked that U.S. military aid to the junta be stopped, as is mandated by U.S. law if such a pattern is proven.

In reply, Deputy Secretary William P. Clark Jr. voiced U.S. support for the Salvadoran government, charged that the guerrillas were responsible for thousands of the deaths, and discounted Amnesty's sources of information.

"The general issue of human rights investigations in El Salvador," Clark wrote, "is complicated by the participation of the local human rights organizations in political activities. The Salvadoran Human Rights Commission has several members who represent armed leftist groups."