Fresno County sheriff's detectives found the gun under some garbage in a trash can in the alley behind the Ellis house. They were already suspicious of his wife, Kathryn. She called 911 that night in September 2012 and reported hearing an intruder shoot her husband.
But when detectives got there, they didn't think she looked like someone who had tried to revive a dying man.
"This is a photo of how the defendant looked the night of the incident after it occurred," said prosecutor Stephanie Savrnoch. "She told the detective she did not clean up in any way. These are her hands and the evidence will be she had not one drop of blood on her."
Bills and financial records show the Ellis' money situation was dire. And a financial advisor says Kathryn Ellis had recently asked about secretly increasing the life insurance on her husband.
But her defense attorney says Ellis sticks to the story she told on the 911 call and to investigators: She didn't kill her husband.
"Not a negative word is going to be said about her treatment of Bob or Bob's treatment of Kathy," said defense attorney Antonio Alvarez. "They had a very loving, close relationship."
But detectives say several details of the story Kathryn Ellis told them didn't check out. For instance, she said the intruder arrived as she and her husband lay in their bed. Her husband went alone into the living room, where he was killed.
"This is the photo of the bed right after the murder before officers touched anything," Savrnoch said as she showed a bed that looked relatively undisturbed.
Detectives say a 259-pound man like Robert Ellis would have left an impression in the bed. But investigators may have trouble explaining the fingerprint found on the sliding door on the right side of this patio.
Ellis' attorney says it didn't match Kathryn Ellis, Robert Ellis, their son, their relatives, or even their gardener. The trial is expected to last a couple weeks and Ellis is planning to testify in her own defense.