OCEANSIDE — A state appeals court today upheld the first-degree murder conviction and life without parole sentence for a man who gunned down his neighbor — a female Navy corpsman — at the Oceanside apartment complex where they lived.
Eduardo Arriola, 31, was convicted by a Vista jury of murder and a special circumstance allegation of lying in wait for the July 20, 2018, killing of 24-year-old Devon Rideout.
Both Arriola and Rideout were residents of an apartment building at 550 Los Arbolitos Blvd., where prosecutors said Arriola shot Rideout five times at around 4 p.m. that day.
Prosecutors say Rideout, Arriola’s downstairs neighbor and a Navy hospital corpsman stationed at Camp Pendleton, was walking her dog when Arriola shot her. After the shooting, he repeatedly claimed to bystanders and police that she was a trespasser.
Investigators searched the defendant’s car and found the victim’s last name scrawled in black permanent ink on the radiator tank. A list of other names and words was also written on the tank, with the final entry “R.I.P.” concluding the list.
Arriola was a former Marine who was discharged for desertion and later diagnosed with schizophrenia, leading to four hearings between the killing and his trial to determine whether he was mentally competent to stand trial. Three separate doctors found him competent, according to court documents.
In his appeal, Arriola’s attorney argued his schizophrenia diagnosis should have meant he was incompetent to stand trial, but a three-justice panel of the Fourth District Court of Appeal ruled Arriola failed to show that the various doctors’ opinions about his competency weren’t supported by evidence.
His attorney also challenged the jury’s finding on the lying in wait special circumstance allegation, which made Arriola eligible for a life without parole sentence. On appeal, his attorney argued that the evidence didn’t show he waited for Rideout and ambushed her.
The appellate panel disagreed, stating that evidence at the murder scene suggested Rideout was surprised by her killer. The court also wrote that when noting Rideout’s name on his car’s radiator tank and a book found in Arriola’s apartment that explained gun laws regarding self-defense and how to legally eject trespassers, “the evidence indicated Arriola planned to kill Rideout under the guise of self-defense” and that the jury was reasonable to determine “that the encounter between Arriola and Rideout was not a coincidence, but rather the result of a planned surprise attack.”
The appellate court did agree with Arriola that the trial judge should not have imposed a firearm enhancement when sentencing him. The firearm enhancement added a 25-year-to-life term on top of the life without parole sentence.
The appeals court agreed that the judge applied the wrong legal standard by finding that the firearm enhancement would endanger public safety if it wasn’t imposed.
“The trial court did not appear to consider Arriola’s future dangerousness if it dismissed the firearm enhancement given that Arriola would never be released due to his life without parole sentence for the special circumstance,” the appellate panel wrote.
The case will return to a local court for resentencing, at which time a judge could impose the firearm enhancement again or dismiss it.
Rideout’s mother sued the federal government for allegedly failing to prevent Arriola from legally purchasing the murder weapon, which he bought at an Oceanside firing range about two months prior to the killing.
The lawsuit alleges that with Arriola’s diagnosis and his discharge from the military, a background check should have prevented him from buying the gun. The civil case remains pending, with a trial date set for February of next year.
