RCMP arrested Travis Edward Vader, 38, a person of interest in the case of a missing couple from Alberta. (RCMP)

RCMP in Alberta say they have arrested a second man along with Travis Vader, whom they describe as a person of interest in the disappearance of Lyle and Marie McCann.

Vader, 38, is now in custody at the Edson, Alta., detachment on outstanding warrants, police said. He was to be interviewed about the disappearance of the couple, who were travelling from Alberta to B.C. in a motorhome pulling an SUV.

The second man was arrested Monday morning with Vader at a home in Niton Junction, about 150 kilometres west of Edmonton. Police did not release his name or any pending charges. He was being questioned Monday afternoon, they said.

The McCanns — Lyle, 78, and Marie Ann, 77 — were last seen getting gas on July 3, shortly after they left their home in suburban Edmonton on their way to the Vancouver area.

The couple's motorhome was found burned to a shell at a campground near Edson on July 5, but the missing-persons investigation didn't begin until July 10, when their daughter reported them missing after they didn't meet her as planned at the airport in Abbotsford, B.C.

Six days later their SUV, a Hyundai Tucson they had been towing behind the motorhome, was found west of Edmonton.

Vader and the other man were arrested before dawn Monday in an operation involving constables from the RCMP's SWAT team. The men were taken into custody without incident, police said.

Vader, who is from Niton Junction, has a criminal history dating back to 1995, when he was convicted of stealing a vehicle.

Travis Vader was arrested early Monday near Niton Junction, Alta., about 150 kilometres west of Edmonton. (CBC)

He was wanted on the outstanding warrants before being named a person of interest in the McCann case.

RCMP Sgt. Tim Taniguchi said police would scour the area around where Vader was arrested.

The RCMP received more than 130 tips about Vader's whereabouts, along with another 170 tips about the McCanns and their vehicles, Taniguchi said.

"The investigators have some information that Mr. Vader has a knowledge of the whereabouts of the McCanns," he told CBC News.

A McCann family member declined to comment on the arrest, but Vader's mother said she's relieved her son has been taken into custody.

Jennifer Vader said she wanted her son to turn himself in.

With files from The Canadian Press