Pete Renteria, who killed his grandparents and an uncle during what is believed to have been a psychotic episode in January, was taken into custody on Saturday, September 30 following his murder of another man.
At the time Renteria was captured, authorities did not know who he was or of his connection to the January slaughter of his relatives.
On January 30, 2023, one of the residents of a home located at 4804 Ramona Place, a usually quiet cul-de-sac in the unincorporated San Bernardino County area known as the West End situated north of Chino, south of Montclair, west of Ontario and east of Pomona and the Los Angeles County line, came into the domicile just after 9 p.m. There he found the lifeless bodies of three other residents of the home, Sonia C. Ramirez, 68; her husband, George M. Ramirez, 72; and their son, David Ramirez, also known as David Renteria, 43. The three had sustained multiple gunshot wounds.
Deputies with the San Bernardino County Sheriff’s Department were summoned to the 1,350-square foot, two-story three-bedroom home at 9:09 p.m. Deputies working out of the Chino Hills Sheriff’s Station, which is roughly 6.4 miles from the home, were dispatched to the scene, arriving there after a driving time of about 11 minutes.
During the initial investigation, nearby residents said they heard what they thought were fireworks going off earlier in the evening.
Though Ramona Place falls within an unincorporated county district, properties there bear Ontario mailing addresses, as the Ontario Post Office provides mail delivery to that area.
When Pete Renteria, the grandson of George and Sonia Ramirez, the nephew of David Renteria and one of the five occupants of the residence at 4804 Ramona Place, had not returned as of mid-day on January 31, the sheriff’s department identified him as a person of interest in the investigation.
After two-and-a-half weeks of investigation, the San Bernardino County Sheriff’s Department on February 17 identified Pete Renteria as the likely killer of George and Sonia Ramirez and David Renteria.
Pete Renteria, when he was 18 years old had been charged on February 25, 2012 with a violation of Penal Code § 246.3(A)-F: discharge of a firearm with gross negligence in the City of Fontana, for which he had been convicted and served 487 days confinement as a result. He was charged on December 7, 2013 with another felony, Penal Code § 246-F: shooting at an inhabited dwelling/vehicle/etc. in the City of Upland. He was convicted in that case and sentenced to three years in state prison.
In 2020, Renteria was again charged on May 7 of that year with another felony, a violation of Penal Code §  29800(A)(1)-F: being a felon in possession of a firearm, and was convicted 19 days later, on May 26, 2020, of that charge. He was sentenced to 16 months in prison with the proviso that he would have to serve half that time.
Investigators learned that Pete Renteria had been diagnosed with paranoid schizophrenia and that he was in a constant state of fear based upon both real and imagined circumstances in his life. He had, on occasion, evinced or expressed a fear of members of his own family. For that reason, he had armed himself on multiple occasions in the past. From 2019 until January 2023, the San Bernardino County Sheriff’s Department had responded to over five dozen disturbance calls or welfare check requests at the Ramona Place address.
Pete Renteria’s bouts of paranoia had been controlled in the past by the administration of anti-psychotic medication.
In the course of his brushes with the law, he had also been arrested and convicted of use, or being under the influence, of a controlled substance and had failed to make several court appearances. He was also charged with a violation of community supervision and the terms of his past probation. He had been subject to a court order in 2016 that he participate in a domestic violence counseling and educational program.
On February 17, the sheriff’s department offered an unequivocal statement that Pete Renteria was considered the primary suspect in the killings of George and Sonia Ramirez and David Renteria, and that he was regarded as a fugitive. For nearly seven-and-a-half months, Pete Renteria had not openly returned to 4804 Ramona Place, and his whereabouts remained unknown.
Based upon conversations with Renteria’s family members and the physicians that treated him, investigators learned that when Renteria went off of the anti-psychotic medication that had been prescribed for him, which has for most users undesirable side effects, symptoms of his mental illness would manifest, altering his behavior and leaving him prone to episodic violence. This represented a danger, as his fugitive status made it difficult or perhaps even impossible for him to get access to that medication, which he was already disinclined to regularly administer to himself, leaving him in a psychotic and volatile state.
It turns out that the 29-year-old Renteria had not gone far afield from Ontario.
According to a posting on the Upland Police Department webpage on September 30, “On [Saturday] September 30, 2023, at approximately 11:55 AM, officers responded to a shots fired call at the southeast parking lot of Memorial Park. Eyewitnesses who were at the scene described seeing the suspect flee the location in a southwest direction immediately after the shooting. Upon their swift arrival, officers successfully located and apprehended the suspect in close proximity to the scene. In addition, officers retrieved what is believed to be the handgun used in the incident. Preliminary investigations suggest that the suspect had been involved in a prior altercation with the victim at the same location. It appears that the suspect returned later to specifically target the victim. As such, this shooting is believed to be a targeted incident and not a random act of violence against members of the public.”
The information provided by the department continues, “The victim is a 34-year-old male out of Upland who was suffering from multiple gunshot wounds. Officers and members of the San Bernardino County Fire Department rendered aid to no avail. The victim was pronounced deceased at the scene.”
The Sentinel has learned that the suspect taken into custody was Pete Renteria.
The department’s September 30 posting stated, “The area around the southeast parking lot of Memorial Park has been thoroughly inspected and has been rendered safe. Residents and visitors can feel assured of their safety. We express our gratitude to the vigilant witnesses and the swift response from our officers, ensuring the safety and security of our community. We are committed to maintaining a safe environment for our residents and visitors.”
Saturday morning, at the time of the shooting, Memorial Park was full of people, as a youth baseball game was in progress within close proximity to where the shooting occurred. Slightly more distant, a sponsored “shredding event” was taking place, one in which paper shredders were on hand for Upland residents to use in destroying documents containing sensitive information. Shortly after the shooting, San Antonio Hospital, the grounds for which are adjacent to the park, was temporarily locked down.
Pete Renteria was remanded to the custody of the sheriff’s department, and was booked into West Valley Detention Center in Rancho Cucamonga. He was being held there on two separate grounds, one of those being an arrest warrant on murder, California Penal Code 187(a), charges pertaining to the deaths of his grandparents and uncle. He is also being held on the basis of the fatal shooting at Upland Memorial Park. He is being held without bail. He is scheduled for a court appearance on October 24 at 8:30 a.m. in Department 15 at the Rancho Cucamonga Courthouse.
-Mark Gutglueck