Police, a Miami-Dade circuit judge and officials with the state's juvenile justice agency are looking into the death of a 17-year-old boy who collapsed Monday night at the Miami-Dade juvenile detention center of a ruptured appendix.

Sources familiar with the boy's death said the teen had been complaining for two to three days of stomach pain and had suffered from vomiting and diarrhea. Nevertheless, sources said, the boy was not taken to a doctor or the hospital for treatment.

A source who viewed the boy's records Tuesday say they do not show the boy ever seeing a doctor.

Miami-Dade Circuit Judge Cindy Lederman, who heads the county's juvenile court, was briefed Tuesday morning by officials with the state's Department of Juvenile Justice, which runs the facility. ''I want to know if this child received quality medical care,'' Lederman said of teen Omar Paisley.

''I need to determine why this child died,'' Lederman added. ``Once we make that determination, we will be very involved in setting up procedures to prevent anything like this from happening in the future, if this was a preventable death.''

Specifically, Lederman said, she is asking officials whether the youth was examined by a doctor.

Omar pleaded guilty Friday to battery charges stemming from an incident in which he cut another youth with a soda can. He was being held at the Miami-Dade Regional Juvenile Detention Center while awaiting a bed at Bay Point Schools, a Miami-Dade school for troubled teens.

Omar's condition worsened at about 9 p.m. Monday, and paramedics were summoned to the lockup on Northwest 27th Avenue. Sources say paramedics performed CPR on the teen, in front of 15 or 20 other children, before leaving the facility at 9:36 p.m. Omar was already dead at about 10 p.m. Monday when he arrived at Jackson Memorial Hospital.

`PREVENTABLE'

''It appears that this child's death was preventable, and that the quality of care he received was substandard, if not criminal,'' said Miami-Dade Public Defender Bennett H. Brummer, whose office represented Omar, and looked into the boy's death Tuesday.

``He was no hardened criminal. This was a child who died in state custody because the state did not provide him adequate medical care. The state of Florida prosecutes parents for child neglect and abuse when those parents are providing better care than the state provided in this case.

''We recommend that this matter be thoroughly investigated,'' Brummer added.

For the past year, Miami Children's Hospital, in Coral Gables, has provided medical care at the detention center under contract with DJJ. In a prepared statement, DJJ officials said they had asked Miami Children's to place medical staff on duty the night Omar died on administrative leave ``pending completion of the investigation.''

''This is a tragic incident,'' said DJJ Secretary William G. ''Bill'' Bankhead. ``I am very upset and extend my deepest sympathies to this young man's family. I am committed to a full and thorough investigation of this incident.''

WORKING WITH POLICE

The investigation, Bankhead said in his statement, ``will include a comprehensive review by a team of medical professionals. The department is also working closely with the Miami-Dade Police Department on their investigation, which is routine in the instance of death.''

An official at Miami Children's Hospital said the hospital was cooperating with DJJ in its probe, and could not discuss the boy's death.

OMAR'S LAST DAYS

''Miami Children's Hospital shares in the sense of grief surrounding the loss of this child,'' Dr. Deise Granado-Villar, director of preventive medicine and health promotion, said in a prepared statement.

On Thursday morning, Omar met with a prosecutor, his lawyer, juvenile justice and school officials to discuss his case. At the staffing, the youth agreed to plead guilty in court and attend a residential program for troubled teens. Sources say Omar appeared fine at the staffing.

Cherry Williams, 40, Omar's mother, saw the teen Friday when he appeared before Circuit Judge Mindy Glazer to plead guilty to the battery charges he faced. Williams also spoke to Omar later that night by telephone.

''He was not complaining of any pain or anything,'' Williams said.

Sources told The Herald Tuesday that Omar began experiencing pain, together with vomiting and diarrhea, by late Saturday or early Sunday.

NURSE DIDN'T GO IN

A juvenile detention center nurse talked with Omar several times during the next three days. But sources say the nurse never actually examined Omar, because she was caring for a toddler at home, and was afraid she would become infected with some intestinal virus that could harm her own child.

''She didn't go in the room,'' said a source familiar with the investigations. 'She said, `I'm not going in there. I don't want to bring anything home to my 13-month-old. She just said to Omar: `Lay down and sweat it out.' ''

A source said correctional officers largely ignored Omar's pleas, as well. Four youths detained at the facility held the teen up so he could vomit, sources said, and helped change his clothes and linens. Sources said the boys reported seeing blood after Omar regurgitated.

Williams was planning to visit her son Wednesday at the detention center.

But at about 9 p.m. Monday night, she got a call from a detention worker who said Omar ``was complaining he had a stomach virus and was vomiting.''

Within a half-hour, Williams said, she was told Omar was being taken by ambulance to Jackson.

A paramedic called Williams to ask whether the boy was taking any medication. Very soon after, someone from the hospital called and asked Williams to drive to Jackson immediately.

''Omar was a loving son,'' Williams said. ``He was lovely. If I fussed at him, and he would leave mad, he would always come back in the door and smile.''