New details are expected in the mysterious disappearance and deaths of the McStay family. San Bernardino County Sheriff's are expected to hold a news conference at 9:00 a.m. Friday.

VICTORVILLE, Calif. (CBS 8 / CNS) -- The ex-business partner of a Fallbrook man who mysteriously disappeared with his wife and two young sons has been arrested on suspicion of murdering the entire family, authorities announced Friday.

Charles Ray Merritt, 57, (aka Chase Merritt) was arrested Wednesday afternoon in Chatsworth in connection with the deaths of Joseph McStay, 40, his wife, Summer, 43, and their sons, Gianni, 4, and Joseph Jr., 3, according to the San Bernardino County Sheriff's Department.

He was scheduled to be arraigned on four counts of murder in Victorville court Friday, but the arraignment was postponed so that Merritt can choose a defense attorney. Merritt showed no emotion during his brief court appearance.

Investigators believe Merritt acted alone in killing all four family members, Sheriff John McMahon told reporters at a news conference in San Bernardino. The cause of death for everyone was blunt force trauma that occurred in the family home, he said without elaboration.

Merritt helped build products for Joseph McStay's fountain design and manufacturing company. In an interview with CNN, Merritt admitted he was the last person to see the McStays alive, saying he cooperated with investigators from the beginning.

The suspected motive was also withheld.

"Although we can never bring them back, I hope that on some level this brings them closure," McMahon said, referring to extended family members who were at the 9 a.m. news conference. He also thanked law enforcement for not giving up on the case.

The McStays' skeletal remains were found last Veterans Day -- more than three years after they went missing -- by a motorcyclist who was riding in an open area west of Interstate 15 near Victorville.

The boys' remains were identified using DNA testing, while dental records confirmed the adult bodies were those of their parents.

Joseph McStay ran a successful business selling customized decorative water features, such as indoor waterfalls.

The last known confirmed sighting of the family was on Feb. 4, 2010. The family appeared to have left their northern San Diego County home in a hurry, according to investigators.

Deputies found their two dogs at the house, and nothing inside suggested the couple and their children had gone on a vacation or other routine trip. A carton of eggs was left on a kitchen counter, investigators said.

Last year, CBS News 8 profiled Merritt, an ex con, and compiled detailed background information on his criminal history, which included convictions for burglary, grant theft and receiving stolen property.













This YouTube video is provided by the

. It shows the arrest Charles "Chase" Ray Merritt in connection with the murders of the McStay Family.