Detectives first thought the prime suspect in the 1995 killing of Robert "Bobby" Mendes had fled to his family's native Cape Verde, but Arnaldo "Nardo" Lopes never surfaced.

Investigators continued to work the case over the years, but say Lopes apparently went underground and assumed an alias, "Michael Eric Hernandez." Police chased rumors that Lopes ventured back to Dorchester, but no firm evidence of his whereabouts ever materialized.

That all changed about a month ago, officials said yesterday, when investigators received intelligence that had them scrambling across the Eastern Seaboard to track down Lopes. The effort culminated with Lopes's arrest Monday at a Maryland airport, as he returned from vacation in Jamaica.

Thomas Larned, an assistant special agent in charge of the FBI's Boston office, said yesterday that a team of Boston investigators and members of the FBI's Violent Fugitive Task Force went to New York and Philadelphia before they found an address for Lopes in Maryland.

They watched the home, then learned over the weekend that Lopes was in Montego Bay on vacation, Larned said. Investigators determined that he was traveling under his alias. They decided to arrest him as soon as he walked off the plane with his girlfriend at the Baltimore airport, knowing he wouldn't be carrying a weapon on the flight, Larned said .

"I got the call, he's in custody, and I called down and congratulated them all," Larned said. "There had been a tremendous amount of work done in this investigation over 10 years and I knew how important the arrest was to investigators and the city of Boston."

Lopes, 28, is being held without bail in Anne Arundel County Detention Center in Maryland after a court hearing yesterday and has until June 1 to decide whether to fight extradition to Boston, the Associated Press reported. He was arrested Monday on a warrant for unlawful flight to avoid prosecution, but also faces second-degree murder charges in connection with the stabbing death of Mendes on a Dorchester street corner.

Lopes has been the subject of intense law enforcement interest since he first fled Boston in the days after the killing, which set off waves of violence in Boston's Cape Verdean community and led Mendes's mother, Isaura, to become a leading anti violence activist.

Larned said that when he joined the FBI's Boston office in 2001, Boston Police Superintendent Paul Joyce told him "this was the priority fugitive case that they wanted us to focus resources on" because of the retaliatory violence it had sparked.

Police Commissioner Edward F. Davis said yesterday that there were many unconfirmed sightings of Lopes in Boston over the years, but that he doubts they are legitimate. "It's hard to say exactly where he was during the course of time, but the general feeling of detectives is that he was out of town," Davis said in an interview.

Davis also said he believes police have made strides in improving cooperation the city's Cape Verdean residents in recent months. "Signs are hopeful," he said.

Denise Gonsalves , executive director of Cape Verdean Community UNIDO, said the arrest is important and signals a new era in the community's relationship with police.

"It's been 12 years, and this is an issue that folks have wanted solved for a great deal of time," she said. "The commissioner has said he is all about community policing and he has taken some steps to create relationships on the ground level going up."

Isaura Mendes also lost a second son, Alex, to homicide last year, a crime that remains unsolved with no suspects or eyewitnesses.

Brian Ballou of the Globe staff contributed to this report. Shelley Murphy can be reached atsmurphy@globe.com, and Suzanne Smalley at ssmalley@globe.com.