A relative who expected frequent contact from Larissa Flores triggered the investigation after her messages abruptly stopped in late July.
LITCHFIELD PARK, Ariz. — The investigation that would uncover two bodies behind a suburban Arizona home began with something far less unusual: a relative who could not reach his mother. By Aug. 4, days had passed without the communication he normally received from Larissa Flores, prompting him to ask Avondale police to check on her, her husband, Hector Flores, and their adult son, Matthew Christopher Flores Semyonov.
That request set off a chain of discoveries that transformed a missing-family call into a double-homicide investigation. Officers found evidence of significant blood and an attempted cleanup inside the Litchfield Park residence, then investigators located two buried bodies on the property. The remains were identified as Hector, 69, and Larissa, 63. Authorities named their 27-year-old son as a suspect, concluded he had left the United States and began an international search that remains active.
According to reporting based on the Avondale police report, the relative who contacted authorities said he had last heard from his mother July 29. Their usual pattern of contact made the silence unusual enough that other family members also tried reaching the couple. Calls and messages went unanswered. Police sought location information from cellphones belonging to the three family members, but investigators were told the phones had been turned off, preventing officers from locating them that way.
The concerned relative eventually met officers outside the family residence on Aug. 4. He provided access to the house but did not accompany police inside, telling investigators he was afraid of what they might find. Details of parts of the officers’ initial entry were redacted from the police report released publicly, but Avondale police later disclosed that the interior contained a large amount of blood along with evidence that someone had tried to conceal or remove it. No member of the household was found there.
With the three residents initially unaccounted for, investigators searched the property and focused on the backyard. By Aug. 6, two bodies had been recovered from buried locations behind the residence. Police later confirmed they were Hector and Larissa Flores. Early medical examiner information listed the causes and manners of death as pending. Officials have not publicly released a detailed reconstruction establishing exactly when each victim died, the precise manner in which they were killed or the full sequence of events investigators believe occurred in the house.
Flores Semyonov was also missing, but authorities did not continue treating his disappearance in the same way as his parents’. Investigators identified him as the principal suspect and said they believed he had fled the country before officers searched the home. On Aug. 7, Avondale police asked the U.S. Marshals Service District of Arizona for help locating and apprehending him. Federal authorities obtained a warrant charging him with unlawful flight to avoid prosecution and began coordinating with international law enforcement partners.
The investigation also drew on what Flores Semyonov’s relatives told detectives about family relationships before the deaths. One family member said Flores Semyonov had learned that his father was having an affair. According to that account, he was upset not only with his father but also with his mother because she had decided not to leave the marriage. The police report records that information as a relative’s statement. Authorities have not publicly demonstrated that the dispute was the sole or established motive behind the killings, and the allegations against Flores Semyonov have not been tested in court.
Relatives described other changes as investigators tried to understand the period before the family disappeared. The report says Flores Semyonov had changed significantly while in college and later moved back into his parents’ home. A relative said he became less social and stopped drinking alcohol. The same witness recalled him making vague threatening remarks, including “you’ll get what’s coming to you.” Police also recorded a family account of an incident in which he watered plants at night and said the plants had told him they were thirsty.
The report references a mental health diagnosis that was redacted from the publicly available material. That information does not establish a cause for the alleged violence. Authorities have not announced that a psychiatric condition explains the deaths, and the public record does not support diagnosing Flores Semyonov beyond what relatives reported to officers. The family statements are significant because investigators collected them while building a timeline, but they remain one part of a case that also includes physical evidence recovered from the home and property.
As detectives pursued the homicide inquiry, the victims became more clearly known publicly. Hector Flores was an associate professor of management and human resources at Cal Poly Pomona. The university said he joined the institution in 2015, taught strategic management and related courses, conducted academic research and served in faculty governance. His earlier career included years in private industry, experience the university said he brought into his teaching. Colleagues described his contributions to students, faculty committees and the broader campus community.
Larissa Flores was a psychiatric nurse practitioner who worked with Circle the City, a Phoenix-area organization that provides health care to people experiencing homelessness. The organization mourned her as a compassionate colleague whose work affected patients and co-workers. Public records and employer statements about Hector and Larissa offered a different picture of the couple than the crime scene that brought their names into national coverage: one built around education, health care and professional service.
A representative for the Flores Semyonov family said relatives were devastated, were cooperating with investigators and wanted privacy. The statement also expressed gratitude to people who had reached out to the family. Police, meanwhile, have continued to withhold significant details about the criminal investigation. Publicly released reports contain redactions, investigators have not described all evidence they believe links Flores Semyonov to the deaths, and there has been no adversarial court hearing at which prosecutors would be required to present their case.
The Marshals Service says Flores Semyonov is wanted by Avondale police on allegations of first-degree murder, dangerous domestic violence and abandonment or concealment of a dead body, in addition to the federal flight charge. Federal officials have described him as 6 feet tall and about 177 pounds with blue eyes. They have not disclosed where outside the United States they believe he may be or whether investigators have narrowed the search to a particular country.
More than a month after the welfare check, the most immediate part of the case remains unresolved: Flores Semyonov has not been publicly reported in custody. His U.S. Marshals wanted profile remained active as of Sept. 22. What began with a relative noticing an unusual break in everyday family communication therefore remains an open international fugitive investigation, while Avondale police continue handling the underlying case surrounding Hector and Larissa Flores’ deaths.
Author note: Last updated September 22, 2026.