An Alexandria man in a drunken stuper showered a woman with an inflammable liquid last October, ignited and left her, burned and bleeding on the floor of the room they had been renting. Three days later a maid discovered the woman and called for help.

The man pleaded guilty to felonious assault last May. He was given a three-year suspended sentence and was placed in probation by an Alexandria Circuit Court judge.

As that sentence was taking place, a second Alexandria man, appearing in an adjoining courtroom, was sentenced to serve nine months in jail. His crime was writing bad checks worth $150. He had already repaid more than $1,400 for other bad checks. In addition he was given a three-year suspended sentence for attempting to cash a bad check for $350.

Prosecutors say it happens all the time. They say their files are filled with similar examples of disproportionate sentencing, such as one man being sentenced to 10 years in prison for car theft while another gets five years killing a friend, or two people who are convicted of the same crime getting different sentences.

That's the way the judical system works said Fairfax County Commonwealth's Attorney Robert F. Horan Jr. The sentences basically are fair, Horan said, because different circumstances warrant different treatment for each offender.

Others, like Alexandria Commonwealth's Attorney William L. Cowhig, say a narrower range of possible sentences for an offense or one flat penalty with no chance of parole would be more equitable, especially for prisoners.

A presumptive sentence plan, in which offenders would be given flat sentences for each offense rather than be subject to a range of penalties, is being pushed by Marshall Coleman, Republican candidate for Virginia Attorney General.

Under the plan, which was rejected in the Virginia House Courts of Justice Committee several years ago, offenses would be punished by a flat sentence rather than allowing a wide range of penalties. Only under extraordinary circumstances could a judge deviate from that sentence.

If the person were a repeat offender, two, three or more years would automatically be added to the sentence.

An extension of the plan would eliminate parole for criminals. Instead, inmates would be awarded good behavior points as credit toward an early release. Prisoners would serve at least two-thirds of their sentences as opposed to the one-fourth that is required now.

Edward Lane, Coleman's Democratic opponent for state attorney general, said he would not comment on the presumptive sentence plan because he did not want to discuss campaign issues until later in the race.

Because inmates would be forced to serve more of their sentences, the severity of penalties would be reduced under Coleman's plan.

For example, an armed robber can be sentenced to from 20 years to life in prison. If he is sentenced to 30 years he is eligible for parole in 7 1/2 years.

Under Coleman's plan an armed robber may face a flat sentence of perhaps 30 years and be eligible for parole in 20 years.

"We wouldn't have these monstrously long sentences that everybody knows is a fiction anyway," Coleman said. Having criminals serve more of their sentences "isn't good for (criminals). It's good for (the public)."

Presently, in cases decided without juries, prosecutors recommend a sentence based on the offender's prior record and examinations by probation officers. In most cases, judges abide by those recommendations.

Under Coleman's plan, neither prosecutors nor judges would have much choice in the sentence.

Horan, the Fairfax prosecutor, said "I have never really liked that kind (presumptive) of sentence. There is such a wide variety between one robbery and another, one burglary and another. There is no such thing as a good murder, but there are some that are worse than others.

Horan recalled the murder and robbery trials of two brothers two years ago in which a drug dealer was killed. Robert Poole was convicted of both charges and received life in prison. His brother, George A. Poole, was sentence to serve 25 years for the crimes. In that case Robert Poole actually fired the fatal gunshots while his brother watched, although both were charged with murder.

There are different circumstances for every crime, Horan said.

For instance the man who received a suspended sentence for setting fire to his girlfriend, was not sent to prison on the condition that he regularly attend Alcoholics Anonymous while on probation three years. The man said if it hadn't been for his drinking problem, the incident never would have happened.

And the man convicted of writing bad checks received a prison term because he had a history of writing bad checks, according to court records.

A wide disparity in sentences exists in rape cases because the penalty ranges from five years to life. Ann Warshauer of the Alexandria Commission on Women said the ranges for penalties for rape should be reduced and categorized according to the severity of the rape.

A survey by Alexandria prosecutors of rape convictions in that city from 1974 to 1976 showed that rapists received sentences ranging from three years (a judge had reduced a jury's verdict) to 25 years.

A man convicted last year of murdering and raping a 5-year-old Alexandrian girl was sentenced to serve 20 years for the rape, 20 years for the murder and five years for abduction.

Coleman said he hopes his plan will reduce the disparity in sentences in different parts of the state. He and some prosecutors said sentences are usually more harsh in southside Virginia, more lenient in Northern Virginia and in the middle in the Tidewater area.

Ted Bennett, Halifax County Commonwealth's Attorney, said sentences vary state-wide to reflect the different attitudes of the community where the crime occurs.

"We try to keep the sentencing on a parity throughout the district," Bennett said. The sentence imposed, "depends on what happens in the case. Anytime you have the human element trying to decide, you're going to get disparity.

But both Coleman and Cowhig said legislator can do just as well deciding statewide community standards that judges or juries.