Jonathan Michael Hearn was described by someone who knew him as "the smartest man he's ever met."
But that same man, according to redacted Kern County Sheriff's Office reports, said Hearn, 24, of Hesperia, was capable of murder and it couldn't be "put past him."
Hearn is charged with first-degree murder in the death of Robert Limon, 38. Police say Hearn shot him twice in the head on Aug. 17 at a Burlington Northern Santa Fe Railway industrial complex in Tehachapi.
Earlier court filings say Hearn and Limon's wife, Sabrina Limon, 35, were having an affair.
During deputies' interviews, Limon's BNSF co-workers described him as "easy-going" and "fun-loving." They didn't know anyone who would want to hurt him.
But the reports also contain interviews with Limon's friends, Jason and Kelly Bernatene, who painted a different picture of events leading up to the murder.
The Bernatenes knew both Robert and Sabrina Limon. Jason considered Robert his best friend.
Jason told his wife he had "a weird feeling" about Hearn, according to the reports. As time passed, Bernatene confronted Hearn about his relationship with Sabrina. He suspected an ongoing affair.
Bernatene told police Hearn "lost his mind" and started yelling at him when asked about the relationship with Sabrina. In response, Bernatene said "that's my best friend's wife and you need to leave us alone."
On a separate occasion, when Bernatene told Hearn to end the relationship, Hearn started "ranting" and was "creepy and scary."
It was Bernatene who described Hearn as "the smartest man he's ever met" and murder couldn't be "put past him."
Hearn later told Jason he and Sabrina had kissed. Police found several text messages between the two with Hearn telling her "I love you" and "You're beautiful."
According to earlier court filings, Sabrina exchanged thousands of text messages with Hearn prior to the homicide, including one in which Hearn told her that with her husband out of the picture they could live their lives together.
The probable cause declaration says Sabrina Limon told Hearn where her husband was working and his schedule the day of the killing. Investigators said in the declaration that video surveillance captured Hearn fleeing the scene just minutes after Robert Limon was shot twice in the head.
Kelly Bernatene was good friends with Sabrina. After Robert Limon's death, according to the reports, she told her husband that following several conversations with Sabrina she was "95 percent sure Hearn was involved" in the killing and "65 percent" sure Sabrina knew about it.
In the week's after her husband was found dead, Sabrina's Facebook page had posts in remembrance of him.
Hearn was arrested Nov. 18 for the killing.