It was just the sort of television program that 15-year-old Ronney Zamora might have watched.

Its ingredients were homicide, a police investigation, a fascinating trial - in short, the stuff of television's crime show fare that so captured the imagination and some say the mind, of this Costa Rican immigrant youth.

Ronney Zamora did not watch this drama on television. He was on the "set," a Dade County courtroom, on trial for murder. And television, the medium that Zamora's defense attorney called "his instructor, his brain-washer, his hypnotizer," was taping every second and telecasting two to three hours of excerpts nightly on Miami's publice station.

The state rested its case yesterday after Miami Beach police Sgt. Paul Rantanen testified that the defendant confessed to him that he shot and killed Elinor Haggart, 82, last June 4. Defense attorney Ellis Rubin has acknowledged that Zamora fired the fatal shot, but he is arguing the boy's innocence by reason of insanity.

Rubin will call on psychiatric witnesses in the coming week to butress his argument to the jury that Zamora "could not distinguish whether he was in a television play acting it out, or whether it was cold-blooded, premeditated murder." Rubin also hopes that actor Telly Savalas, star of "Kojack" on CBS-TV, will be allowed to testify Wednesday on the influence that crime program might have had on Zamora.

Rantanen testified that Zamora gave two confession, both acknowledging that he killed Haggart, but differing in details. Rantanen conceded, on cross examination, that niether confession was tape recorded or written down because, he said, "Ronney was willing, almost eager, to tell me the story."

According to the officer, Zamora related the following sequence:

He and a companion, Darrell Agrella, then 14, needed money and knew that Haggard kept some at her home, next door to the Zmora family's house. Haggart returned home, discovered the pair and threatened to call the police. The youths tried to persuade her not to do so.

Meanwhile, Zamora, was said to have admitted, they had searched the house and found and envelop of money and Haggart's 32-cal, revolver.

It was at this point that Zamora's two purported confessions diverged. In the first, Rantanen said, Zamora told him, "I don't know what happened. The gun just went off." Then, the story continued, Haggart asked for a drink of whiskey, and when Zamora returned with it, the woman "fell over," apparently dead.

In the second confession, which Rantanen said he considered more truthful, the boys chatted with Haggart for an hour and a half, during which Zamora poured her several glasses of whiskey and water before she accepted one that was to her liking. They looked at photographs of Haggart and her late husband. They thought that Haggart was persuaded not to call the police, but ultimately she said that she intended to do so.

"So I took a pillow, and I wrapped the gun in the pillow, and I shot here," Zamora was quoted as saying.

Then, according to both purported confessions, the boys ransacked the house, wiped away their fingerprints and took two television sets and other articles to Agrella's house where teh police later found them.

The state also called four teenage boys to testify that Zamora took them on a weekened pleasure trip to Walt Disney World near Orlando, within hours after the slaying. The four said they did not know at the time that Haggart had been killed or that the car Zamora drove belonged to the dead woman. They said Zamora paid most of their expenses for two days from $415 that he carried.

During all the testimony, Zamora usually stared ahead, showing no outward reaction. Slightly built at 5 feet 3 inches tall and 130 pounds, he looked as if he belonged more in sidewalk game of marbles than in a courtroom on trail for murder.

The presence of television marked the first extensive TV coverage of any Florida trial since the state supreme court opened courtrooms to electronic coverage on July 5 for one-year experiment. None of the participants seemed to pay the camera much heed. There was no evident posturing by the participants.