It started as a routine traffic stop along busy I-95 in South Carolina on Friday morning. State Trooper Bruce K. Smalls had received a report that a motor home was being driven erratically. Squad car lights flashing, Smalls pulled the vehicle over.

Smalls approached the 33-foot Holiday Rambler and had a brief conversation with the three occupants, state police said. He was then shot six times at close range with a .38-caliber handgun -- twice in the heart, once in the face and three times in the chest.

When state police responded to an emergency call from a trucker, they found Smalls dead on the pavement. In the motor home they found the body of the vehicle's owner -- C. Daniel Swansen, a 52-year-old real estate developer from Fairfax County.

Swansen, who was married and had three children, had been shot once in the head at point-blank range, also with a .38-caliber handgun, according to Jasper County, S.C., coroner J. Martin Sauls.

A longtime Northern Virginia resident, Swansen had built single-family homes all over Fairfax County. His last big project was Briarwood, a development in Annandale.

Swansen's body was wrapped in a bedsheet and a quilted bedspread, and stuffed behind the camper's bed, the coroner said. His head was wrapped in four or five large towels, and his body bound with heavy-gauge stereo speaker wire at the legs, waist and neck, Sauls said.

He said the wire had been fashioned to form a kind of carrying handle.

Sauls said Swansen had apparently been killed early Friday morning, no more than eight or nine hours before the 9:30 a.m. shooting of the trooper.

Two men and a woman, all described by South Carolina police as without jobs or fixed addresses, were arrested on I-95 shortly after the shooting of the trooper and each has been charged with one count of murder in the trooper's death.

Authorities said the three are also being investigated in connection with Swansen's killing, but no charges have been placed in that death.

They have not yet determined where he was killed or why, said Roberts Vaux, a South Carolina prosecutor for the region in which the trooper was slain.

"The motive for the killing of the highway patrolman is that he would find Mr. Swansen's body," said Vaux. "But we have yet to find a motive for killing Mr. Swansen."

Nor do South Carolina authorities know why the developer was in their state, or where he was headed.

Swansen, described by associates as semiretired, had been in North Carolina on vacation with his wife, Deanna.

According to the victim's mother, Frances Swansen, Deanna Swansen had returned to Fairfax County on Thursday for a medical appointment, and neither she, nor the couple's three children, Mark, 25, David, 17, and Linda, 16, heard from Swansen again. The victim's wife could not be reached yesterday.

Some time last week, Swansen had taken the camper to a travel park in Emerald Island, N.C. The facility was evacuated as Hurricane Gloria approached.

Police speculated that the three persons in the motor home when the trooper approached may have been picked up by Swansen somewhere on the road after he left the campground.

Some associates questioned whether Swansen, whom they described as cautious, would have picked up hitchhikers. But Frances Swansen suggested it was not necessarily out of character. "He was a good person," she said. "If he saw some young kids, he probably thought he'd give them a ride in his lovely motor home. And, maybe he was lonely from being on the road."

Friends describe C. Daniel Swansen as a private person, more comfortable in the company of one or two close friends than in a large group.

They said he remained depressed over the death of a son in a motorbike accident several years ago.

As a developer, associates said, he was especially skilled at shaping a project to suit the requirements imposed by the site. "He was just an excellent developer," said John Attiliis, a longtime friend and associate.

When his last large project, the Briarwood subdivision off Braddock Road, was 75 percent complete, he sold the remaining lots to another developer and concentrated his energies on another enterprise in Cary, N.C., near Raleigh -- the Williamsburg Manor town house subdivision, which he had developed, and where he continued to maintain rental properties.

Full details of his activities in the past few days were not immediately available. His mother said Swansen and his wife left Fairfax in late August for a North Carolina vacation. Swansen, an avid boater, kept a motorboat in the Washington area, and moored a sailboat in Oriental, N.C., near Pamlico Sound. The couple also enjoyed traveling between campgrounds in their motor home, she said. The manager of the travel park in Emerald Island, where they stopped last week, said she did not remember the couple.

According to his mother, after Deanna Swansen returned to Fairfax County, Swansen was to drive to a new location, and then telephone his wife, so she could rejoin him.

Upon finding Swansen's body and that of Trooper Smalls, police fanned out along the highway. They picked up one suspect -- Richard C. Johnson, 22, of Royal Palms, Fla. -- two miles north of the scene, hitchhiking on I-95, heading north.

Johnson offered no resistance. A .357 Magnum handgun was found in his duffle bag, according to State Police Sgt. G.L. Sims. Johnson is currently being held at the Kirkland Correctional Institute in Columbia, S.C., pending a bond hearing today.

The other two suspects approached police on I-95 about 45 minutes after the shooting and said they wished to be witnesses, Sims said. They were identified as Julie Sue Smith, 19, of Nashville, and Curtis Harbert, 20, of Moorefield, W.Va. Both are being held, pending a bond hearing, at the Jasper County Law Enforcement Center.