A Colorado man arrested last week in connection with a triple homicide in Forestville had been traced to the Gulf Coast but was apprehended almost by chance when sheriff's deputies near Mobile, Ala., pulled him over on a routine traffic violation, a law enforcement official there said Tuesday.

Mobile County deputies Thursday morning stopped Mark William Cappello on Interstate 10 not realizing until they ran his license plate that Sonoma County authorities had issued an order for the white 1995 Ford Bronco he was driving to be seized pursuant to a search warrant, Mobile County sheriff's spokeswoman Lori Myles said.

The deputies also weren't aware Cappello and the vehicle had been identified in a "be on the lookout" notification issued for the area by Sonoma County investigators, Myles said.

"I don't know how they had tracked him down to this area, but somehow they knew he was on the Mississippi/Alabama Gulf Coast," she said.

Cappello, 46, has family in southern Florida's Fort Myers area, although it's unclear if he may have been headed there.

Cappello's mother, Mary, said by phone Tuesday she hadn't spoken with him in the past week, but he recently said he might be coming for a visit. She said she didn't know of his arrest.

Sonoma County detectives were among law enforcement officers from several jurisdictions who conducted a search of Cappello's home in Central City, Colo., the night before his arrest, according to a neighbor.

Cappello's girlfriend also was contacted at her restaurant job and detained for several hours of questioning, said the neighbor, Ron Montoya. Her cellphone and other personal property were seized for examination.

Cappello was arrested on suspicion of murder in the Feb. 5 slaying of three men, including another Colorado man, during what investigators believe was to have been a drug sale in a rural home off Ross Station Road and Highway 116. He is being held without bail.

Those slain were Sebastopol native Raleigh Butler, 24, whose mother rented the house, Richard Lewin, 46, of Huntington, N.Y., and Todd Klarkowski, 42, of Boulder, Colo., about an hour's drive from the suspect's home in Central City.

It remains unclear how the men might have known one another or whether there are additional suspects.

Sonoma County Sheriff's Lt. Dennis O'Leary, who oversees violent crimes investigations, said only that authorities did not believe there were suspects remaining in Sonoma County.

O'Leary otherwise declined to answer most questions submitted to him Tuesday, saying officials "are not going to comment because we don't want to jeopardize our ongoing investigation."

That's the same reason authorities gave for not making public Cappello's Thursday arrest. They disclosed it late Monday afternoon after The Press Democrat received a tip about the arrest and began to inquire.

O'Leary has said investigators believe the three victims gathered at the house on a wooded rural parcel to buy a large quantity of marijuana.

It is unclear how Cappello came to detectives' attention or what evidence points to him as the killer. O'Leary said authorities are withholding information about evidence from the crime scene and anything they might have found in Cappello's home or car to preserve the integrity of the investigation.

O'Leary said Cappello did not resist when he was stopped in his car outside Mobile. A warrant was then issued for his arrest in the homicide case. He was booked into the Mobile County Metro Jail, where he was being held without bail awaiting extradition.

O'Leary said Cappello declined to be questioned by detectives and has requested a defense lawyer.

He said Cappello could be returned to Sonoma County for prosecution late this week or next unless he legally challenges extradition.

Ron Montoya, the suspect's neighbor in Central City, said Cappello seems an unlikely murder suspect. He also said Cappello's girlfriend appeared to have no inkling, either, that he might be connected to the triple homicide.

"He's kind of a homebody," Montoya said. "He's a very straight kind of guy."

He said Cappello bought his house about 2? years ago, landscaped it and maintains it meticulously.

Cappello doesn't hold a regular job, but said he has family money and an interest in family businesses, including one that takes him to Brazil for weeks at a time, Montoya said. He also brings a horse trailer up to the house a couple times a year and leaves for New Mexico, saying he's delivering horses, Montoya said.

Montoya said Cappello serves on the city's powerful Historic Preservation Commission and is a vocal participant in the governance of the historic mining town, which is a National Historic site and a community of fewer than 700, with an economy largely dependent on casino business.

City Manager Alan Lanning said Cappello was appointed to the post in December 2010.

"I don't know at this point if there's any connection between him as a person and the murders," Montoya said, "but it's very, very hard to believe."

You can reach Staff WriterMary Callahan at 521-5249 or mary.callahan@pressdemocrat.com.