When Lillian Gibson found the word "Nigger" painted on the street in front of her suburban Prince William County home, she dismissed it as an annoying but harmless prank.

Mrs. Gibson and her husband are black. But they didn't think about race when they rented their $425-a-month home in the Independent Hills subdivision in July 1978. "You don't think of these things in the 1970s," Mrs. Gibson said.

But now the Gibsons are convinced they are the victims of a steadily escalating campaign of racial hatred that has placed their safety in jeopardy. They are ready to move if those responsible aren't caught.

In the last year, their home has been pelted with eggs, shot at twice, and the grass in their front yard scorched into the shape of a cross.

The cross burning happened two weeks ago while the Gibsons were asleep. They never heard a sound.

"When I woke up Sunday mornng," Mrs. Gibson recalled, "there was this black, ugly cross in the front yard."

The vandals struck again at 1:20 a.m. Sunday, firing five or six shots, apparently from a high-powered rifle, into the Gibson home. No one was injured. Two bullets ripped through the metal front door, one exploded through the wall of an empty front bedroom, landing inside a closet.

A 7-year-old daughter of Gibson's husband from a previous marriage, who spends every other weekend at her father's home, was there this weekend. Usually, Mrs. Gibson said, the child sleeps in the bedroom that was fired upon. But Saturday night, for the first time, she slept in another bedroom. "Maybe I had ESP," Mrs. Gibson said about moving the child. "If the child . . . or anybody had been in that bed, they would have been killed," she said.

When she opened her front door immediately after the shooting, Mrs. Gibson said, she also found a green, plastic bag full of "stinky, smelly" deer offal.

Mrs. Gibson, who runs a janitorial service, and her husband Ernest, a truck driver, say they have no idea who is behind the attacks. Mrs. Gibson said they are not active politically and have no enemies.

"We just think its because we're black," she said, speaking in a fast, nervous voice. "It is like a Ku Klux Klan-type of thing."

Prince William County police officials said yesterday they have had no indication the Klan is active in their area.

Police Sgt. Harold Morgan said investigators have no idea who is behind the attacks.

The Gibsons are the only black family on their street, which is part of a rural subdivision about 10 miles south of Manassas.

A woman neighbor said she was "very sad" over the attacks on the Gibsons. "They are real nice," she said, "one of the best neighbors I've had."

For now, the Gibsons are not spending nights at their home.

"I can't understand someone pulling a trick like this in 1979," she said sadly. "It doesn't make any sense."