(CNN) — Almost a year to the day after an off-road motorcyclist found the remains of a California family who had vanished from their home in 2010, authorities announced Friday they had arrested the man they believe is responsible for the deaths.

Charles “Chase” Merritt is charged with four counts of murder in the deaths of Joseph and Summer McStay and their two small boys, San Bernardino County, California, District Attorney Michael Ramos told reporters at a news conference.

Merritt, 57, was arrested Wednesday without incident in Chatsworth, California, Detective Chris Fisher said.

Police say they believe the family died of “blunt force trauma” inside their home north of San Diego, but they declined to discuss specifics of the deaths or a motive.

Merritt, who was a business partner of Joseph McStay’s, was scheduled to be arraigned Friday afternoon, Ramos said.

In an earlier interview with CNN, Merritt said he received a phone call from Joseph McStay the night they disappeared, but didn’t answer it because he was busy and tired.

“There are hundreds of scenarios,” he told CNN at the time. “I have gone over all of them in my head. Of course I regret not picking up the phone.”

On Friday, McStay’s brother, Michael McStay, choked back tears in thanking investigators for their work on the case.

“You have no idea what this means,” he said.

Police who searched their home days after the family disappeared found eggs on the kitchen counter and bowls of popcorn in the living room, along with the family’s two dogs. There were no signs of a struggle.

Despite finding the family’s SUV in San Ysidro, California — where it had been towed from the Mexican border — and video surveillance that showed a family matching the description of the McStays crossing the border, authorities had no clue what happened to them until the discovery of their bodies on November 11, 2013.

A motorcyclist passing through the area found the remains in two shallow graves not far from Interstate 15 in San Bernardino County, more than 100 miles from the family’s home north of San Diego.

Authorities identified the remains using dental records. At the time, San Bernardino County Sheriff John McMahon said the killings appeared to be “extremely orchestrated” and carried out by more than one person.

But after reviewing 4,500 pages of investigative records, executing 60 search warrants and conducting 200 interviews, investigators zeroed in on Merritt, concluding he had acted alone in killing the family in their own home, San Bernardino authorities said.

He declined to say what specifically led them to that conclusion.

Fisher did, however, say there was no evidence the family had traveled to Mexico after their disappearance, calling the border video “unrelated” to the case.

“We don’t think it’s them,” he said.

Ramos said he has not yet decided whether he will seek the death penalty in what he called a “cold and callous murder of an entire family.”

Joseph McStay’s mother credited investigators for their strength and determination to solve the case.

“I need justice from the law and the courts and to get to talk to the judge,” she said. “And most of all, justice upstairs for my lovely family.”

CNN’s Randi Kaye, Jessica Small, Melissa Dunst Lipman, Dana Ford, Greg Botelho and Chandrika Narayan contributed to this report.

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