The McStay family disappeared from their home in 2010 and their remains were found buried in shallow desert graves in the Mojave Desert in 2013.
Judge Michael Smith has unsealed 33 of the 35 warrants. Some of the information was removed for privacy concerns.
Among the details, a business associate Daniel Kavanaugh told detectives Joseph McStay loaned accused killed Charles Merritt $30,000 to pay gambling debt. He also said Joseph was planning to fire Merritt.
McStay, Kavanaugh and Merritt were partners in an online fountain business called Earth Inspired Products. Merritt was the custom designer and builder. Merritt also told detectives he didn't like Kavanaugh and stated "If I were ever going to commit murder, it would be with him." Detectives also said they noticed when referring to McStay, Merritt used past tense "Joseph was".
In examining McStay's computer, four checks totaling just over $15,000 were electronically written from McStay's business account following the family's disappearance.
3 of the checks were backdated then deleted, the checks also appeared to be forged. 76 checks were missing from the account.
Merritt admitted to signing McStay's name to three of the checks.
Detectives also found he tried to delete the account. In a 100-minute phone call to Intuit, he claimed he was "Joseph McStay" and company records show he changed the contact number from McStay's number to his own phone. Cell phone records of Merritt's phone show him making the call to Intuit.
When confronted about the changes, he told investigators Joseph McStay instructed him to make the changes. Merritt did not make the changes until after their last meeting and it was not until days after he claimed he lost contact with McStay.
In the murder investigation, the grave site for the family of four was just a few miles from Merritt's sister's home. Detectives said Merritt was the only person with knowledge of the high desert in the investigation. Prosecutors have also argued Merritt was placed near the gravesite location through pings to cell phone towers.
Cell phone records in the investigation also showed the McStays were in Fallbrook when they disappeared. Joseph, nor Summer's cell phones were never found, detectives said they believe the murder suspect took them.
Investigators also concluded, the crime of murder was committed at the Fallbrook home. It is believed Merritt bludgeoned the family of four to death, then used paint to cover the blood. Detectives said correct forensic processing would still show blood stain and could still be detected years after.
Blood or DNA was never found at the Fallbrook home, however, detectives said a sledgehammer and the bra on Summer McStay found in the grave site had paint matching the paint in the home.
According to the documents, Merritt was the only person in the investigation with knowledge of the high desert where the McStay family remains were discovered and his sister lives a few miles from the grave sites.
Following the McStay's disappearance, when interviewing Merritt detectives noticed a fresh wound to his hand. He told them he cut it on fresh metal. He also told investigators he had health problems from recent stent surgery. Home video of the McStays with Merritt taken months before the family went missing showed Merritt jumping over a fence and climbing a mountain next to the McStay home. Investigators said the video indicates Merritt was healthy and his injuries were exaggerated to throw the investigation.
Merritt's home was also searched, numerous computers and storage devices seized. The warrants also said detectives also found notes on the McStay investigation and several quotes that had to do with "remorse, forgiveness and murder".
Warrants also revealed Merritt told San Diego County Sheriff's investigators that he did not like Joseph's wife Summer McStay.
A trial has been set for 57-year-old Merritt in August. He pleaded not guilty to charges in the murders of the McStay family.
Merritt initially did not seek an attorney claiming he did not have the money to hire one. He also claimed he had congestive heart failure and only had 6 months to live. In early June, Merritt ended up hiring Jimmy Mettias.