A 46-year-old man was arrested late Wednesday in the District and charged in Fairfax County with the murder of a former lawyer for the Securities and Exchange Commission.

The body of Eric N. Miller, 45, was found in the trunk of a burning Ford Taurus in the 900 block of Third Street SE on Aug. 31. He had apparently been fatally beaten in the head, the D.C. medical examiner's office ruled.

D.C. police began a homicide investigation but turned the case over to Fairfax police when they "discovered some things that linked [the suspect] to Fairfax County," Fairfax police spokeswoman Mary Mulrenan said.

Mulrenan said detectives were able to determine the actual location of the homicide: a room at the Alexandria Motel, on Route 1 in the Alexandria area of the county. Police believe Miller was killed Aug. 29, two days before his body was found. Mulrenan declined to say how police identified where or when Miller was slain.

About 10 Wednesday night, D.C. police arrested Dana E. Moro, 46, who had no fixed address. By then, Mulrenan said, Fairfax police already had a warrant charging Moro with murder.

Police declined to discuss a motive for the killing, other than to say that Moro and Miller had an argument, Mulrenan said. Sources close to the investigation said the motive might have been related to drugs or debt.

Fairfax detectives traveled to the District and questioned Moro later Wednesday, Mulrenan said. D.C. police obtained charges of felony destruction of property and fugitive from justice, and Moro was being held in the D.C. jail yesterday pending extradition to Fairfax.

Miller lived in the 5600 block of Upland Woods Drive, just south of Alexandria in Fairfax County, with his wife and two sons. He grew up in Alexandria, the son of A. Melvin Miller, a former civil rights lawyer who later chaired the city's housing authority and school board.

Eric Miller graduated from St. Stephen's Episcopal school, Amherst College and Harvard Law School and worked for several Washington law firms before joining the SEC in 1999. He left the SEC in May for unknown reasons.

He was memorialized in a service Wednesday that filled the Zabriskie Chapel of Immanuel Church-on-the-Hill in Alexandria. The service was attended by Mayor Bill Euille, former city manager Vola Lawson and other longtime Alexandria residents.

Friends of the Miller family described them as "pillars of the community."

"She was so proud of him," said Ginger Primus, a 30-year colleague of his mother, EulaMiller, at Northern Virginia Community College, where Eula Miller runs the early childhood development program.

Primus said Wednesday's memorial service focused on Miller's intelligence.

"He was an amazing young man who everyone said was the smartest person they had ever met," she said.

"He was the one that raised the bar, so to speak, for the ones that came after," she added, referring to Miller's younger sister Ericka and younger brother Marc, who spoke at the service.

"They said that they were always trying to live up to his reputation and fill his shoes. The younger son talked about how he remembered when he finally grew taller than his brother, which was great for basketball." Since Miller's death, she added, "he said, 'Now I'm looking up to him.' "

Wendy Blair, who attended Amherst College with Miller in the early 1980s, described him as "a funny guy" who "wore the typical preppy look."

"We used to talk about politics and argue about it; it was a lot of fun," she said. "This was the Ronald Reagan days, and he was probably more supportive of him than I was."

Fairfax General District Court Judge Mark C. Simmons grew up with Miller in Alexandria and said Miller was a voracious reader, a huge Redskins fan and a devoted coach of his son's Little League teams.

"All of Alexandria will miss the guy," Simmons said, "because he was really well-known, well-liked and well-respected."

Staff writers Del Quentin Wilber, Jerry Markon and Henri Cauvin contributed to this report.