There was a time when Frank J. Coppola, a convicted murderer scheduled this week to be the first to die in Virginia's electric chair in 20 years, thought about becoming a priest. He was only a teen-ager, but he was serious enough to leave his native Portsmouth and enroll in a six-year Catholic seminary outside Baltimore.

As it turned out, Coppola dropped out of seminary and later out of college, choosing in August 1965 to become a policeman instead. But the 6-foot, former college basketball star--known for his quick temper and a flamboyant, tough-guy manner--survived only two years on the Portsmouth police force.

"Frankie was a good policeman, but he got jammed up," said a fellow officer. "He had some problem and he got jammed up."

Fifteen years later, Coppola sits in a white basement cell at the Richmond State Penitentiary, around the corner from the massive electric chair that has been prepared to receive him at 11 p.m. Tuesday. By all accounts, the 38-year-old prisoner is still determined to die, as resolute now as he was last March when he abruptly dropped his legal appeals and asked the state to carry out its four-year-old death sentence.

For four months, Coppola has maintained a public silence, refusing all interviews except with a high school acquaintance from a Tidewater paper who has agreed not to print anything until after the execution. In a letter to his attorneys, Coppola explained only that he would rather die than live in prison.

"It is my honest intention to rescue any semblance of dignity I have left," he said. His only request was that his execution take place after the school term was over so he could spare his two teen-age sons even more trauma.

Lawyers and friends who have visited him say Coppola was sincere in stating his reasons for dying. In particular, they point to the effects of living on Death Row at the Mecklenburg state prison, where Coppola has spent most of his prison time. It is a prison described by some as "a hellhole" and it is among the most restrictive in the country.

In fact, Coppola--regarded as one of most articulate and forceful of the 18 inmates on Virginia's Death Row--helped initiate a lawsuit brought by the American Civil Liberties Union challenging the conditions at Mecklenburg as cruel and unusual punishment.

"Those conditions were very clearly a significant factor in his decision," said Alvin Bronstein, an ACLU lawyer who has been in close contact with Coppola. "He couldn't face spending any more time there. It was changing him as as a human being."

In the last week, as his tenacity in regard to his dramatic decision became more apparent, pressure built for Coppola to change his mind and for Gov. Charles S. Robb, on the record as a supporter of Virginia's death penalty, to commute his sentence or grant him a temporary reprieve.

Letters, some with foreign postmarks, have been pouring into the governor's office urging a stop to the execution, which, if it takes place, will be the fifth in this country since 1967. As of Friday, Robb had received 238 letters on the Coppola case; only 13 urged him to let the prisoner go to his death.

The state NAACP also gave its voice to the swelling protest, even though Coppola, like the other four men executed in this country since 1977, is white. Capital punishment, said Virginia NAACP director Jack Gravely, is "not a black-white issue. It transcends race, creed and color." Yet Virginia history gives black leaders cause for concern: Between 1908 and March 1962, when 27-year-old Carroll Garland became the last Virginian to die by execution, 235 men and one woman were put to death by the state--and of those, 203 were black.

There was also a flurry of legal activity this week as three different groups argued for a reprieve on the grounds that Virginia's death penalty, revised in 1977, is still constitutionally weak and should not be used until it has been thoroughly reviewed in the federal courts.

But so far, there is no sign that these legal arguments--still under review by Robb--have shaken the view, upheld by the Virginia Supreme Court in its review of the case in 1979, that the death penalty would be properly applied against Coppola.

The death sentence was recommended in Coppola's case on Sept. 26, 1978, on the same day and by the same jury that had convicted him of murdering Muriel Hatchell, the 47-year-old wife of Peyton Hatchell, a prosperous used-car dealer from Newport News.

It's unclear why Coppola, his second wife Karen Evans, his friend Joseph Miltier and Donna Mills targeted the Hatchell household for burglary in the spring of 1978, although Newport News police theorize that the group was aware that Hatchell had been known to carry payroll cash in his car.

Coppola and Miltier had been arrested together once before, and were convicted of breaking into the Princess Anne Equipment Company in June 1971, for which Coppola served a year in prison.

Police do know however, that the group had tried to enter the Hatchell home once before when Coppola appeared at the door disguised as a priest a few days before the acutal murder. The ruse did not work and Mrs. Hatchell kept her door shut.

On the day of the murder, Donna Mills went to the Hatchells' door, posing as a delivery woman with a bouquet of roses. Once in the house, Mills pulled a pistol out from among the roses and made way for Coppola and Miltier.

The two men tied up Mrs. Hatchell with cords from venetian blinds and, according to testimony in the trial, struck her in the face and beat her head against the floor to get her to tell where her husband hid the money. There was also testimony that Coppola, with socks over his hands, tried to choke Mrs. Hatchell.

The beating was still going on when Hatchell walked in the door and was struck on the head with a pistol. The group fled, taking $3,100 in cash and some rings. By the time help arrived, Mrs. Hatchell was dead--killed by head injuries and asphyxiation caused by her own vomit.

All four who participated in the burglary (Evans was in a getaway car a mile away) were arrested, but only Coppola was given the death penalty. Miltier, although also implicated in the beating of Mrs. Hatchell, was given life imprisonment. "It was a different jury," said Lt. Bobby Campbell, who was in charge of the investigation. "And besides, Coppola was more of a ringleader."

To his old colleagues in nearby Portsmouth, news of Coppola's arrest for murder came as a shock. Some, looking back, remembered that he was given to bizarre types of behavior, like snatching spiders off the jailhouse walls and eating them, apparently to show how tough he was. "From what we heard," said Campbell, "he was the type of individual who was not afraid of anything."