LAGUNA BEACH, Calif. (CBS 8) -- It has been five weeks since the skeletal remains of Joseph and Summer McStay and their two young sons were found buried in the high desert near Victorville.
CBS News 8 investigated several people associated with the Fallbrook family that went missing in February 2010, and then was found murdered on November 11.
Michael James McFadden is the current husband of Joseph McStay's ex-wife, Heather; and the step-father of Joseph's McStay's now 17-year-old son by the first marriage.
A few months before the McStay family disappeared from their Fallbrook home on Feb. 4, 2010, Summer McStay filed a Child Protective Services complaint against McFadden, according to Joseph McStay's father, Patrick McStay.
CPS investigations are confidential, so the exact nature of the complaint cannot be confirmed.
"No one knows what the CPS report said because we're not allowed to see it," Patrick McStay told CBS News 8 in an interview from his home in Texas. "I have evidence that there were threats made, after the CPS report, to Joey and Summer."
Patrick McStay claimed the threat was made by McFadden, and was related to the CPS complaint allegedly filed by Summer McStay.
"I know that Joey had discussed going for custody of his eldest boy. I know that there was a CPS report. I have found evidence that there was a threat. I found my son's notes that tell me what was going on, and McFadden is named in the notes," Patrick McStay said. "To me, that is enough to investigate this guy."
McFadden, 49, works at a jewelry store in Laguna Beach, once owned by his father-in-law.
McFadden hung up when reached on the telephone by a CBS News 8 producer, so we sent a camera crew by his store. He has not been named as a suspect in the McStay murders and declined to answer questions about the case.
Court records show McFadden is an ex-con who served prison time following a felony, domestic violence assault 15 years ago.
In July of 1998, Huntington Beach police officers arrested McFadden after the brutal assault that caused great bodily injury to his then girlfriend, a mother of four children, according to court records.
"Michael McFadden broke into my house and repeatedly punched me, head butted me, choked me, kicked me… telling me he was going to kill me. I believe had I not escaped I would not be here today," the victim wrote in a declaration in support of a restraining order.
The woman, who CBS News 8 is not identifying, was age 39 at the time of the incident. The beating left her with a "concussion and 30 stitches on my forehead," according to her declaration.
"I ran to my brother's house. The ambulance was called. Michael McFadden fled the scene to his house in Laguna and was arrested shortly thereafter," the declaration continued. "I am afraid for myself and my four children."
The woman included photographs of her injuries in the court filing. There was no indication in the court papers that a weapon was used in the attack.
McFadden, then age 33, was charged in Orange County Superior Court with eight felony counts, including burglary, assault by means of force likely to produce great bodily injury, corporal injury to a spouse (or significant other), terrorist threats, and attempted murder.
In January 2000, McFadden pleaded guilty to a pair of felonies: assault by means of force likely to produce great bodily injury, and terrorist threats. He was sentenced to two years, eight months in prison; and ended up serving 15 months.
"What can you take from this? I mean, I gotta figure this guy is pretty dangerous," said Patrick McStay, Joseph McStay's father.
CBS News 8 wanted to ask McFadden about his criminal history and the CPS complaint that Summer McStay allegedly filed against him. Instead, he escorted our camera crew out of the jewelry store without commenting on the case.
Recently, however, an online forum user with the name Michael McFadden posted the following remarks on the crime-sleuthing web site, Blink on Crime:
I am Michael J. McFadden… I am not a criminal nor did I murder the McStay family… My family is trying to get through this horrible tragedy as privately as possible but I am growing tired of all the name calling and mudslinging toward me… I liked Joey and he was my friend so knock it off!
My "rap sheet" is all from one terrible night in my life. That night was the last time I consumed alcohol. I have been a solid productive member of society since. I am a father, husband and business owner. I love life and have a positive outlook… I committed a crime... years ago. That crime involved myself, my girlfriend and another man. Period. I'm not proud of it but frankly I served my time and never looked back. My family attends church and love God. We love each other and have good lives.