"SOCIETY and the judicial system failed our daughter," write Roberta and Vincent Roper in a letter on this page today. Stephanie Roper was kidnapped, raped and brutally murdered by Jack Ronald Jones, who has just been sentenced to life imprisonment with the possibility of parole after 12 years. "We remain what Jack Jones made us -- life-long victims," write Mr. and Mrs. Roper. "We will never get time off for good behavior."

What would have been a better resolution of this case? Capital punishment would certainly satisfy the sense some people have that the punishment should be equally as severe as the crime. But others, including ourselves, hesitate to sanction the taking of a life. In the Roper case, it seems, the general sense of justice is offended not so much because Mr. Jones received a life sentence instead of a capital one, but because almost everyone assumes he will be automatically released from prison in 12 years.

Things could have been done differently. The law in Maryland could be amended in order to allow a jury to recommend a sentence of life imprisonment without possibility of parole. Or Judge Walter Haile could have imposed consecutive sentences -- Mr. Jones was convicted of first-degree murder, kidnapping and aggravated rape -- instead of concurrent ones. This would have given some future parole board an indication of his intention to provide more than a minimum term. But that is water over the dam.

Still, there is something the Ropers can do. "We demand equal rights for victims as well as defendants," the Ropers say. They do have an important right, and they should exercise it 12 years hence. The fact that Mr. Jones will be eligible for parole in 1994 does not mean it will be granted. The memory of this crime may fade in the mind of the public. The Ropers will never forget. They will be keeping track of the months and years, and they will know exactly when Mr. Jones' first parole hearing comes. They have the right, even the obligation, to make a statement to that board at that time. In their evaluation of the prisoner, the members of the parole board should not be allowed to forget what befell Stephanie.

It may be small consolation to the grieving Ropers, but it is something important that they can and should do for their daughter, and for all of us who valued her innocent and promising life.