"This is a really unusual crime for this small community. Particularly one that would involve domestic violence, it's kind of shocking for a small community," said Corcoran Police Chief Reuben Shortnacy.
Luis Pulido-Esparza, 34, a Correctional Officer at Corcoran State Prison, is in custody at the Kings County Jail.
He's been booked for the murder of his girlfriend.
Corcoran Police say Sunday around 7 a.m., Pulido-Esparza called 911 and reported that his girlfriend had shot herself and was not breathing.
"Originally, he had said that she committed suicide, and he thought it stemmed from an argument they had the night before," said Chief Shortnacy.
Officers arrived and found a 32-year-old woman with a gunshot wound to the head inside a home on Evergreen near Village Drive.
Family members have identified her as Marilu Ramirez Olmedo. Ramirez did not survive.
Detectives were called to start an investigation.
"We discovered it was in fact, not a suicide, Esparza was responsible for the homicide of that individual," said Chief Shortnacy.
Corcoran Police say they recovered the firearm they believe was used in the shooting. It was legally owned and registered to Ramirez.
Officials say they don't have any record of previous domestic violence between the two.
Family members say Ramirez met Pulido-Esparza at work at Corcoran State Prison.
He was a correctional officer and she worked in the Substance Abuse Treatment Facility providing services in the Integrated Substance Use Disorder Treatment program.
The two had been dating for about five years and had a two-year-old daughter together.
Ramirez also had two older boys from a previous relationship, aged 11 and 16.
Police say all three children were home at the time of the shooting.
Ramirez's family members did not want to go on camera or be identified Tuesday for safety reasons but said she was a hard-working mom who adored her children.
"She was a teen mom, but that never stopped her. I think part of it was having support from family, but the other part of it was her drive to do good for her kids," a family member said.
Family members say Ramirez's kids will now be without her as a role model, and the family has lost an independent woman who was silly, and sometimes sarcastic. "I feel like no one can replace her. No one can replace her."
The California Department of Corrections and Rehabilitation released a statement confirming the two worked at the prison.
"The California Department of Corrections and Rehabilitation (CDCR) is deeply saddened by this tragedy and supports the employees at Substance Abuse Treatment Facility and State Prison in Corcoran (SATF). As a result, the Peer Support Program was activated and is providing intervention, counseling and resources to help employees cope with the effects of this traumatic incident."
They say Tuesday is Pulido-Esparza's normal day off, so as of Tuesday, he remains employed at Corcoran State Prison.
Late Tuesday afternoon, the Kings County District Attorney's Office formally filed charges against Pulido-Esparza. He's been charged with first-degree murder and felony child abuse as well as special allegations for use of a firearm.
If convicted, he faces life in prison. He's due in court on Wednesday.
If you are the victim of domestic abuse, or you know someone who is, there is help available 24/7. In Fresno County, call the Marjaree Mason Center at (559) 233-4357. In all other locations, call the National Domestic Violence Hotline at (800) 799-7233.