A woman who launched her own investigation into her aunt's murder discovered the alleged killer was her own boyfriend, authorities said Friday.
Background
The victim, identified as 54-year-old Sandra Martinez, was found dead in her Phoenix home on March 15, 2019, according to police reports. Martinez was discovered by a family member who became concerned when she failed to answer calls for several days.
Phoenix Police Department detectives responded to the scene and immediately began a homicide investigation. Initial evidence suggested forced entry into the residence, though the investigation stalled for lack of suspect information.
The victim's niece, 28-year-old Maria Gonzalez, became determined to find answers after her aunt's death. Over the following months, Gonzalez compiled her own investigation notes, reviewed police reports, and spoke with neighbors in an effort to identify the killer.
The Investigation
In late 2025, Phoenix police detectives received a tip from Gonzalez that led to a breakthrough in the cold case. Through renewed analysis of DNA evidence collected at the scene and additional witness interviews, investigators identified Martinez's nephew, 31-year-old David Hernandez, as a suspect.
Detectives learned that Hernandez had been in a relationship with Gonzalez for approximately two years. When confronted with the evidence, Hernandez allegedly confessed to detectives that he was responsible for his aunt's death.
Hernandez has been charged with one count of first-degree murder, according to court records filed in Maricopa County Superior Court. He is being held without bail at the Maricopa County Jail.
Key Takeaways
- Sandra Martinez, 54, was found dead in her Phoenix home on March 15, 2019
- Her niece Maria Gonzalez conducted her own investigation into the murder
- Police identified David Hernandez, who was dating Gonzalez, as a suspect in 2025
- Hernandez has been charged with first-degree murder and is being held without bail
What's Next
Hernandez is scheduled for a preliminary hearing on May 15, 2026, in Maricopa County Superior Court. Prosecutors have indicated they will seek a grand jury indictment on additional charges.
The Phoenix Police Department has praised Gonzalez's persistence in the case, noting that her tip ultimately led to the breakthrough. Detectives continue to investigate potential motives in the killing.
The case is being prosecuted by the Maricopa County Attorney's Office.