Pedro Armando Arellano, a 27-year-old San Mateo resident, was denied bail after being charged with second-degree murder in connection with his girlfriend's overdose death. The San Mateo County District Attorney said Arellano "remains a danger to the public." Arellano allegedly supplied fentanyl to his girlfriend, Adrienne Dahbour, who overdosed and was found dead the subsequent morning, as detailed in the San Mateo County District Attorney's social media post.
Pedro Armando Arellano (27) was denied bail yesterday because "he remains a danger to the public." Charged with 2nd deg murder, in January, Arellano allegedly provided fentanyl to a female, who then overdosed, & was found dead the next morning. He was arrested by @SanMateoPD. pic.twitter.com/ECFf8AxpjU
— San Mateo County District Attorney (@SanMateoCoDA) August 8, 2025
In court yesterday, Arellano pleaded not guilty to the charges against him. Despite the gravity of the case, he waived his right to a speedy jury trial, possibly to prepare his defense more thoroughly. His decision was reported following his hearing in Redwood City Felony Court. According to the San Mateo County District Attorney’s Office, Arellano and Dahbour were both habitual fentanyl users. On January 4, Arellano allegedly gave Dahbour fentanyl, leading to her fatal overdose, as reported by KRON4.
This isn't the first time the couple faced the life-threatening effects of the drug. Prosecutors shared that Arellano alone had survived three or four previous fentanyl overdoses, while Dahbour had been revived from two overdoses with the help of Narcan. The pattern of use and overdoses suggests a depth of addiction and the perilous grip fentanyl has. On one occasion, San Mateo Police officers had explicitly warned Arellano that he could be charged with murder if someone died as a result of him supplying them with fentanyl, the district attorney’s office stated.
Arellano's legal proceedings are set to continue with a preliminary hearing on April 28, where the evidence brought by the prosecutors will be presented. Until then, Arellano remains in custody without the option to post bail, as reflected by his recent bail denial.
