A conservative lobbying group, with a controversial past, has joined efforts to tighten Maryland's sentencing laws that began after the murder of Stephanie Ann Roper, leaving Roper's family upset and worried that it may have been exploited by the group.

A storm ensued after the Family Protection Lobby (FPL) sent out an emotional letter Dec. 6 over the signature of Roberta Roper, the mother of the 22-year-old Frostburg State honor student who was raped and killed last year.

The four-page letter, which by this week will have gone to roughly 80,000 people, explicitly details Roper's brutal death and the family's pain, asks for readers to attend a Jan. 17 rally at the Maryland statehouse, and, in a postscript, asks for contributions to the Family Protection Lobby because the family's "efforts on our behalf are going to cost them tens of thousands of dollars . . . ."

The envelope also contained a form, with Stephanie Roper's photograph, allowing recipients to check off contributions of $100, $75, $50 and $25 for the FPL.

Although she signed the letter, Roberta Roper said today that she "didn't realize the implications" of affiliating the Stephanie Roper Committee, which she set up to change Maryland's criminal sentencing laws, with the FPL. The FPL was dumped from the Moral Majority because of the FPL's alleged confrontational tactics and has since earned the enmity of dozens of state legislators.

"As far as we knew . . . they were a good conservative group," Mrs. Roper said. "But there have been some very distressing things.

"I did sign the letter but I did have misgivings. It's not my style. I don't feel comfortable asking people for money. When I called the man FPL head James Wright to ask for changes I was told it was too late."

What particularly upset Roper was the tone of the Dec. 6 letter and a follow-up thank you note sent to those who contributed money that asked for a further contribution.

"The Stephanie Roper Committee will remain just that, a separate entity," Mrs. Roper said. "I don't want the politicians saying, 'They're going off the deep end with that group.' "

Wright, who says his group has a membership of 10,000 in Maryland, said today that his sole motivation was to help the Roper committee get its legislation passed and that he had consulted extensively with members of the committee and the Roper family before sending out the letter.

"I think she Mrs. Roper is feeling a lot of pressure, I think people are giving her a lot of grief for our support," Wright said. "All I can say is we put out almost $20,000 to support the rally. I told the committee we want to make sure that people do not think we are trying to exploit the Stephanie Roper incident."

Wright said the letter, which he wrote after receiving a much shorter draft from the committee, has raised $10,300. He said he has stopped sending out the follow-up thank you letter because of the Ropers' objections.

A number of legislators, including vocal supporters of the Stephanie Roper Committee, are concerned about the effect the FPL's involvement could have on the legislation.

"I think the Roper Committee was being used," said Sen. Howard A. Denis (R-Montgomery), a cosponsor of the Roper bills. "It's deplorable. What's suspect here is the extent to which they used a very nice person and a very good committee to their own ends. I hope this won't have a negative effect on the bills and give people an excuse to vote against them."

Another supportive legislator, Del. Charles J. Ryan (D-Prince George's) was shocked when he received the letter, which went out to all state legislators. "I just can't see using a tragedy like this, especially during the holiday season, to try to collect money."

The letter that began the controversy is headed: "Personal from Roberta Roper." It then says, "The pain of Stephanie's death will be all the more real as my family celebrates Christmas in a few weeks. When we exchange gifts, Stephanie won't be there . . . . As we sing Christmas carols Stephanie's voice will be missing . . . . As we put up decorations, Stephanie's memory will burn in our hearts."

The Roper committee legislation would, among other things, eliminate parole for persons convicted of capital crimes, and increase the circumstances under which a person charged with first-degree murder can be tried for a capital offense.