The brother of a youth slain by police bullets evoked Ecclesiastes at a memorial service last night, saying there is "a time to be born and a time to die." When the service was ending, the pastor of St. Francis de Sales Church said it was a time to sign petitions asking for an investigation of the killing.

More than 500 people turned out at the Roman Catholic church, 2021 Rhode Island Ave. NE, to say goodbye to 18-year-old Michael P. Sluby and give their condolences to his family, who filled the first pew. The Rev. John Cunico said in a sermon, "Four days ago, God called Michael. We don't know why. We ask many questions. The answers don't come, at least not very quickly."

Cunico's voice rose in anger at the beginning of the sermon when he pointed to a television crew in the rear of the church and shouted, "Get out!" citing the family's wish that no news media be present. Earlier, a family member had given a Washington Post reporter permission to attend.

The priest completed a liturgy of prayer, communion and song by asking all those who wished to sign a petition calling for an investigation by District of Columbia and Maryland officials to do so on their way out.

Two investigations by Prince George's County police are under way, one by homicide detectives and the other by the department's internal affairs unit.

Even as the memorial service was starting, the site of the shooting -- "The Haunted School," a vacant schoolhouse in Mount Rainier which was decorated for a community Halloween party -- was open for business. A spinning blue light flashed in the atrium of the old building, while a sign that said "Haunted School: Enter at your own RISK" stood on the lawn.

It was early in the morning of last Friday when Sluby and his girlfriend, Candace Jean Craig, also 18, apparently slipped into the school through a broken window on the ground floor, triggering a silent alarm that has been in place since before the school was closed in 1981. Responding to the alarm, Joseph Wing, a 12-year veteran of the Prince George's County police, and Rebel, an 80-pound German shepherd dog, encountered Sluby in the darkened school about 12:40 a.m.

Police on Saturday said the German Shepherd had not attacked Sluby when Sluby fatally stabbed the dog several times with a knife described by police as "rather long." Friends and relatives said Sluby carried a pocket knife with a 2 1/2-inch blade.

After stabbing the dog, police said, Sluby advanced toward the officer and Wing fired two shots into the youth's chest. Craig was not hurt and later was charged with breaking and entering.

Prince George's County police declined yesterday to answer questions about the incident. "We will make a full statement, a full completed, updated release tomorrow morning," said Maj. James Ross. " . . . Nothing today."

"There's not that much I could add," said Robert Craig, father of the dead youth's girlfriend. " . . . As far as I'm concerned, all hell just broke loose and people are still in complete shock."

The abandoned school where the shooting take place was sold Oct. 17 by the county to Gaithersburg businessman Mike Hubert and his brother and father, county officials said.

Hubert said his family had permitted the Prince George's and Mount Rainier Jaycees to use the structure for a "haunted school" to raise funds for the Jaycees.