Hinckley confinement raises anew issue of locking up mentally ill while states look for better ways to monitor them once they are freed

Three and a half weeks after Vernal Walford signed himself out of a Massachusetts mental hospital, he murdered a nine-year-old boy in a Florida motel.

Walford had fallen through the cracks of a mental health system that are deepening into fault lines. While a Massachusetts special senate committee probes the circumstances of Walford's release, the questions of how to predict the dangerousness of mental patients and how long to confine them are of growing national concern.

Mental health workers readily admit the profession is unable to accurately assess which patients remain a danger to society. The field relies heavily on the use of psychotropic (mind-altering) drugs to keep mental patients under control.

Twenty years ago 70 percent of cases were inpatients, according to Dr. Saleem Shaw, chief of the center for study on crime and delinquency of the National Institutes of Mental Health. Today 70 percent are outpatients, largely because of the use of drugs.

This phenomenon has made it more important than ever to closely monitor the progress of outpatients, since a mental patient who appears calm and rational while on psychotropic drugs may prove a danger to society when off this drug diet. Yet many states fail to keep track of mental patients once they leave the hospital.

A unique, low-budget program in Oregon largely attempts to address this problem. The state has established a Psychiatric Security Review Board, which does not emphasize preventing a patient's release but on controlling the circumstances under which he is released.

The four-year-old board supervises all mental patients who have committed crimes and decides when and how they are released. Candice Hammersley, executive director of the board, says the key to its success is in its authority to order the immediate return to the hospital of any patient on conditional release.

Before any such release is approved by Oregon's board, the patient must have a source of income, acceptance at a local mental health center, and a supervised living situation - not with family members, a situation which ''doesn't work,'' according to Ms. Hammersley. A specific supervisor is assigned for each released patient to let the board know monthly of progress.

''You've got to track them,'' Ms. Hammersley says. Oregon is the only state to assign this tracking to a board which is independent of hospitals or courts.

If patients ''miss any appointments, do street drugs, don't take their medication,'' or violate any of the conditions upon which they were released, then a written order from a board member is considered sufficient warrant for any law enforcement official in the state to return them to Oregon State Hospital in Salem, according to Ms. Hammersley. A due process hearing must be held within 20 days.

While the Oregon board's ''primary responsibility is protection of the public ,'' Ms. Hammersley says, ''there is no way we can keep everyone locked up.''

''The best way to protect the community,'' says Dr. Shaw, is through stringent checks on a patient's compliance with the conditions upon which he was released. ''Then we don't have to rely on predictions'' of dangerousness, he says.

One of the cracks in the system that appeared during testimony before the committee hearing on the Walford case revealed that he had been encouraged to enter the hospital voluntarily. This is a common policy since patients are considered more amenable to treatment if they have chosen to be admitted. But it also enabled Walford to voluntarily leave the hospital. Walford was found not guilty by reason of insanity of the ritualistic knifing of the boy and is now in a Florida mental institution.

In Oregon, a pass request by anyone under the supervision of the Psychiatric Security Review Board must be approved by the board.