A California man authorities say was linked through cellphone records to the shallow desert graves where the remains of his business partner and the partner's wife and two sons were found has been ordered to stand trial in the family's slayings.

During a preliminary hearing Monday, investigators testified that Charles "Chase" Merritt's cellphone could be placed near the remote gravesites some 100 miles from the family's San Diego County home and also to a call a few days later to try to transfer and close out his then-missing business partner's online bookkeeping account.

But questions remain about what prosecutors believe happened the day Joseph McStay and his family vanished from their two-story home in Fallbrook in 2010. Or how Merritt's attorneys, who called no witnesses at Monday's hearing, plans to defend him at trial.

Merritt has pleaded not guilty. His attorneys say they hope for a speedy trial to resolve the case.

San Bernardino County Superior Court Judge Michael A. Smith ordered Merritt to face trial following Monday's hearing. He said a key piece of evidence influencing his decision was the discovery of the defendant's DNA on the steering wheel and gearshift of McStay's Isuzu trooper, which was impounded near the Mexican border a few days after the family disappeared.

Smith also cited a sheriff's detective's testimony that Merritt referred to family members in the past tense during an interview with investigators long before anyone knew they were dead.

"When you combine that information with the fact that two days after the disappearance the defendant's cellphone is pinging off of the cellphone tower in the immediate vicinity of where the victims were buried, it all creates a strong inference and strong conclusion there is a probable cause to believe the defendant was a participant in the homicides," Smith said.

Defense lawyer Jimmy Mettias told the judge prosecutors failed to place Merritt at the family's home when the McStays vanished.

"At their best, they put on an embezzlement case today," Mettias said after the hearing. "We're here for a murder case, and we'll take care of the embezzlement at the time of trial."

The McStay family's disappearance initially puzzled investigators. They noted there were no signs of forced entry at the McStay home and the couple's credit cards and tens of thousands of dollars in bank accounts were untouched.

More than three years after the family disappeared, the remains of McStay, 40; his wife, Summer, 43; 4-year-old son Gianni and 3-year-old Joseph Jr. were found in the San Bernardino County gravesites. Also recovered were a rusty, three-pound sledgehammer and a child's pants and diaper.

The elder McStay's remains had an electric cord tied around the neck and was wrapped in a woven blanket.

All four were found to have been killed by blunt force trauma to the head, with Gianni suffering at least seven blows, San Bernardino County sheriff's Detective Edward Bachman testified.

Detectives questioned Merritt two days after a missing persons report was filed, and it was then that it was noticed he referred to the family in the past tense.

"There were also times when he used present tense but he frequently used past tense," San Diego County sheriff's Detective Troy DuGal testified.

San Bernardino County Sheriff's Detective Daniel Hanke testified that he spoke later with a customer relations representative for QuickBooks who remembered receiving a call about McStay's account on Feb. 9, 2010, five days after he and his family vanished.

"He told me the caller identified himself as Joseph McStay," Hanke testified, adding that the call was from a cellphone used by Merritt.

The QuickBooks account was used by McStay to write checks to vendors connected to his water features business.

Authorities testified that Merritt was added as a vendor to the account on Feb. 1 in an update that did not appear to be created by McStay.

The next day, they testified, Merritt cashed a check from the account and two days after that McStay, after logging on to the account, called his bank. The next day he and his family disappeared.

In the days after McStay's disappearance, authorities said, checks for more than $13,000 backdated to that day were cashed or deposited by Merritt.

McStay's brother told reporters after the hearing that knowing the case will move forward will help his family heal.

"We're just grateful you know they got the right guy and they have what they need to put him where he deserves to go," Mike McStay said.