Trouble had been simmering in Baltimore County for some time and James R. Pennington, head of the local branch of the NAACP, was becoming more and more disturbed about it. The crossburnings were bad enough, already four this year in racially integrated neighborhoods in the county. Then Pennington received an anonymous warning from a telephone caller that a NAACP meeting was going to be bombed by a "dangerous" man -- a threat that was never carried out.

But Pennington wasn't aware of the full scope of the trouble until Thursday, when county police and federal authorities announced that, after an 11-month undercover investigation, 10 members of a splinter group of Ku Klux Klan had been arrested on charges of conspiring to firebomb Pennington's Catonsville home.

"I've been telling people about the the problems here for some time," said Pennington. "But I never knew how deep they were."

Civil rights officials pointed to the arrests and the recent spate of cross burnings as evidence of a resurgence in Ku Klux Klan activities in Baltimore County, a traditionally white and conservative community where many blacks, emigrating from Baltimore City, now comprise more than 10 percent of the population.

While Tony LaRicci, the grand dragon of the state KKK, disavowed the eight men and two women suspects and said the leader of the 10 suspects was once banished from the organization because of his "franatical behavior," black leaders expressed outrage and demanded that the group be outlawed in Maryland.

"If a two-legged animal quacks, has a bill and feathers, swims with its feet and acts like a duck," said NAACP Regional Director Emmett Burns, "it's a duck. You can call it whatever you want, but there's a resurgence of Klan-like violence and hatred all throughout the state -- and it's appalling."

The wife of the man police consider the primary suspect in the conspiracy added, "I pleaded with him to get out. If you've got Klan, you've got trouble."

The problems in Baltimore County started long before the arrests. County police reported 29 cross-burnings last year alone. Then, in January, two more burnings occurred in an apartment complex in the western part of the county.

At that point, Baltimore County police began to investigate, and in the last week of that month two police officers, working undercover, found an opportunity to infiltrate an organization know as the Invisible Empire of the Knights of the Ku Klux Klan, which was suspected of committing the cross-burnings.

The group was headed by a Catonsville man, Richard Lee Savina, a disabled truck driver, who formed his own organization after banished from LaRicci's Confederation of the Knights of the Ku Klux Klan. "Mr. Savina turned out to be a misfit, ignorant . . . ." La Ricci said. "He put out literature that had scare tactics."

According to Maj. Walter T. Coryell, who headed the county police investigation, the two undercover officers "traveled in the innermost circles of the group." They went to Savina's home on occasion, and drove with him when he met with various associates, one of whom was William Sickles, the leader of another KKK splinter group in Delaware.

In March, Savina held a ceremony in his home and signed a contract merging his Klan group with Sickles' in Delaware. The two undercover officers, one of them a woman posing as the male officer's wife, had become so trusted by Savina that he presented them with certificates, emblazoned with gold leaf, that proclaimed them "Klansman and Klansperson of the Year."

It was about this time that police became aware of several alleged Klan activities. One of these was a cross-burning at 10:30 p.m. on March 12 at the Woodlawn Senior High School in Baltimore County. A six-foot cross propped against the building was burned, and the words, "You Were Warned" were splashed on a wall.

In early April, Savina, accoring to police, began speaking of bombing some targets in the county, and police contacted the Bureau of Alcohol, Tobacco and Firearms. While talking to ATF agents, county authorities learned that the ATF was already investigating Sickles in Delaware for federal gun violations. The two agencies then joined forces in the investigation.

Then Wednesday, one of the undercover officers was given an incendiary device for safe-keeping. The device was a plastic milk carton filled with gasoline and containing a fuse. Pennington who, as head of the local NAACP, had been outspoken in his criticism of discrimination in the schools and police force, was named as a target, and the police and ATF decided to make the arrests.

Arrests on a range of firearms, conspiracy and cross-burning charges the suspects, in addition to Savina, Sickles and his wife, included four Baltimore men, one Baltimore woman, a Delaware man, and a Paulsboro, N.J., man.

All of the cross-burnings, which police investigated, occurred within a few miles of Savina's Catonsville home, located in an older suburban neighborhood that has been recently integrated. Savina's neighbors said they knew he was a member of a Klan organization, and that on occasion Savina would hang an American flag on one side of his white porch, and a Confederate flag on the other.

Savina's wife, who declined to give her full name, said Friday she often pleaded with her husband to leave the organization he founded. "The Klan is dangerous," she said. "Three-fourths of them are crazy. They don't have the good sense God gave them, people who stand around praising burning crosses. I used to beg him to get out of it, but it was his toy. It was his thing, so I let him have it and he got burned."

About a mile away from Savina's home is the neighborhood where Pennington lives.

"I helped organize the NAACP in Baltimore County three years ago. This is a place where a lot of well-to-do black people have moved," Pennington said. "We're beginning to make our mark on some issues. We're talking about discrimination and bigotry and job opportunities. It's obvious," he said, "that some people don't want us here, much less hear about it.