Although Watts denied the cheating allegations in conversations with police, authorities say their investigations have confirmed the affair with an unknown co-worker.
On closed internet forums about the case, four separate women have been identified as the possible woman involved – including women who reportedly worked alongside the couple as promoters for weight loss patch company Le-Vel.
Forensic profiler Dale Yeager has also suggested a number of motives that may have led Watts to allegedly murder his family.
“For Chris to [allegedly] make the leap from adultery to murder, he had to be at a point where he could get to such a dark place, mentally, that he could justify very ugly, evil behaviour,” Dr Yeager told Hollywood Life.
“People who cheat don’t have a moral compass. If you commit adultery in a relationship, you are a vile person because you’re a liar and a con-artist. You don’t care about the people you hurt, including your own children.”
Watts and his wife Shanann were reportedly also dealing with an "incredible amount of debt" leading up to the incident.
On Thursday, Watts' 15-weeks-pregnant wife Shanann was found buried in a shallow grave on a Colorado property owned by Watts' former employer Anadarko Petroleum.