In the wards for the criminally insane at St. Elizabeths mental hospital, a strange and alien world run by psychiatrists and judges, a killer wins part-time release after 4 1/2 years while a man who stole a coat still fights for unconditional freedom after six.

That world is John W. Hinckley Jr.'s new home, where he mixes freely with some of the capital's more famous and infamous criminally insane, cared for by a professional staff of 300 psychiatrists, social workers and others whose job it is to cure his mental illness and -- when they decide he no longer is dangerous -- to petition a court to free him.

It is a world of about 120 patients judged not guilty by reason of insanity (called "NGI" at the hospital) for a wide range of acts.

Patient Charles G. Woodard, for example, was found NGI after admitting the 1973 killings of four, including a 2-year-old. He was placed in minimum security three years after being committed. Now he is in the hospital most of the time but -- starting 4 1/2 years after he was committed -- has obtained "conditional releases" to attend school and visit his mother in Anacostia.

A staff psychologist testified Wood-ard was a "good risk . . . He's been confronted with the reality of having killed four people and he wants to put that behind him."

Another patient, Michael Anthony Jones, was found not guilty by reason of insanity for stealing a coat more than six years ago. He has obtained conditional releases for daytime and overnight visits in the community, but is still committed to the criminally insane unit long after the one-year maximum he could have served if found guilty and sent to prison. He has appealed to the U.S. Supreme Court, which will decide whether St. Elizabeths can continue to hold criminally insane patients indefinitely.

One widely known alumnus of the hospital's John Howard Pavilion, where the criminally insane are kept in an open dormitory and bedroom setting but behind locked doors and barred windows, is Linwood Gray of Southeast Washington -- charged with 56 counts of conspiracy to import and distribute narcotics, tax evasion and other crimes in allegedly masterminding one of the biggest heroin rings in city history. Gray was found innocent of all but the four tax counts, for which he is now serving U.S. prison time.

Previously, Gray had been found not guilty by reason of insanity for carrying a dangerous weapon and was committed to the Howard Pavilion from 1968 to 1976. From the pavilion he wrote a friend that he was faking mental illness.

He was released to convalesce at home after hospital officials told the court he had "made an excellent adjustment" and no longer was dangerous. Soon after, narcotics officials arrested him and brought the drug charges.

Another patient, James R. Snyder, was found not guilty by reason of insanity of first-degree murder in 1959. In 1963 and in 1972 he escaped from St. Elizabeths and went to New Jersey. Eventually he was found and returned to John Howard. He subsequently was tried and convicted of killing a woman while he was in New Jersey, according to law enforcement authorities. Now he is still living at John Howard and is actively seeking unconditional release from St. Elizabeths.

The pavilion for the criminally insane is arranged into wards of 20 or 30 patients each. Hinckley is allowed, as is normally the case, to mix with the 21 other patients in his ward in hopes this will help him relate to others and understand reality.

There are four maximum security wards, one medium and two minimum -- the latter mostly for patients whom the courts have allowed to visit relatives or hold jobs in the community. In addition, there are two pretrial wards for persons under observation.

Hinckley is housed in a private room in Ward 9, one of the maximum security wards. Last weekend he was allowed, like other patients, to use a telephone in the ward's "day room." He called The Washington Post four times Saturday and Sunday to speak to a reporter, and officials said Monday that his further access to the telephone would be strictly supervised.

According to Harry Fulton and Ross Dicker of the Public Defender Service who work with patients at the pavilion, there is a system of privileges by which patients like Hinckley are progressively given more freedom inside the institution as their mental conditions improve or if doctors think such rewards would be therapeutic. Those privileges are extended without any court action.

Patients in what Dicker called category A are kept inside the building, although they can go outside to a walled sports area for recreation.

Category B patients may go for a few hours "anyplace they feel may benefit them " on the hospital grounds, according to Dicker -- for example, to visit the canteen or simply walk the grounds -- but accompanied by a hospital aide. In category C, patients may do the same thing unaccompanied, either to have some time to themselves or to carry out a small "industrial therapy" job somewhere on the grounds.

Finally, category D patients are allowed out on the grounds from sunup to sundown, from which it is not difficult to escape over unguarded walls and fences.

"I had a guy on serious murder charges on a maximum ward but they had him on a job outside the building," said Dicker. "They treat the individual. This man was a 1974 case and at least by 1978 he had a job on the grounds and was doing very well with it."

Now, Dicker said, this patient has a court-ordered conditional release that allows him to be "out in the community working off the hospital grounds , and he comes back here to sleep."

This system makes escape easier than from most prisons and jails. According to court records, police and prosecutors, escapes from the Howard Pavilion have been numerous. Sgt. Harold Winters of the D.C. police department missing persons bureau said there have been 11 escapes from the pavilion this year -- three of persons judged criminally insane, as Hinckley has been, and eight of persons being held for observation prior to trials or hearings.

While hospital officials said the average criminally insane patient remains housed at the pavilion 4 1/2 years before receiving court-ordered unconditional release, they declined to provide information on recidivism, on the average time it takes patients to obtain privileges and freedoms, or on escapes.

One of the most famous of the missing criminally insane is Harry A. Hantman, accused of raping and fatally shooting a minor in northwest Washington on Aug. 4, 1968. Hantman was acquitted of the killing by reason of insanity and sent to the Howard Pavilion. He had a conditional release in 1972 for "family therapy" at a doctor's office in the community. He disappeared on "unauthorized leave" in 1974 and hasn't been heard from since.

Another described by police as "long gone" is Herman Clark, found not guilty by reason of insanity for first-degree murder in 1963 and granted conditional release by a federal judge in 1967. A year later he disappeared and has not been heard from since, according to police.

Hospital officials yesterday refused to discuss escapes, but in a 1976 Washington Post article Joseph Henneberry, a registered nurse who was then and remains the administrative head of the section to which Hinckley is committed, explained his philosophy that privileges and freedoms are necessary in treatment.

"If you're going to treat an individual, how will you know if he has reached a level of responsibility without taking some clinical chances," he said. "We don't treat crimes, we treat illness."

Dicker of the public defender's office said one of his major concerns is people who were found not guilty by reason of insanity for misdemeanors during the early 1960s, were committed to the criminally insane unit, and have been kept there ever since because judges continue to consider them dangerous.

Dicker called this "the real misuse of the insanity defense" and said that he has recently been able through legal action to get five such individuals out of the criminally insane unit. Some of these people, who were senile, have been civilly committed to St. Elizabeths, he said, and the others are free.

"The doctors don't hold the key to the hospital, the judges do," said Dicker. "A number of judges won't even release someone from this hospital to go serve prison sentences."

Hinckley was taken to St. Elizabeths on June 22, hours after U.S. District Judge Barrington Parker ordered him committed. On Monday, a jury found Hinckley legally insane when he shot President Ronald Reagan and three others in March 1981.

After an initial 50-day observation period, Hinckley again goes before Parker for a hearing to determine if he should be released because he is no longer insane and a danger to the community. If he is not released, he will then have the right to demand a hearing on his mental condition every six months.