Matthew Flores Semyonov faces state homicide-related charges and a federal unlawful flight charge as authorities search for him outside the country.
LITCHFIELD PARK, Ariz. — Federal authorities are leading an international search for 27-year-old Matthew Christopher Flores Semyonov, who is wanted on murder and other charges after his parents were found dead and buried behind their Litchfield Park home.
The U.S. Marshals Service lists Flores Semyonov as wanted by the Avondale Police Department on charges of first-degree murder, dangerous domestic violence and abandonment or concealment of a dead body. He also faces a federal charge of unlawful flight to avoid prosecution. Authorities allege that he killed his parents, Hector and Larissa Flores, concealed their remains and fled the United States. Those allegations have not been tested in court.
The case began Aug. 4, when a relative requested a welfare check after family members were unable to reach Hector Flores, Larissa Flores or their adult son. A newly released police report says the concerned relative had last heard from the couple July 29 and considered their sudden silence unusual. Officers entered the home with a family member’s permission but found none of the three residents inside.
Police have said officers discovered a large amount of blood in the home as well as indications that someone had tried to clean it. The discovery shifted the response from a routine welfare check toward an investigation of possible foul play. Officers initially classified all three family members as missing while detectives worked to determine what had happened.
Investigators later searched the backyard and recovered two bodies from shallow graves. The remains were subsequently identified as Hector Flores, 69, and Larissa Flores, 63. Police have not publicly released a full account of the manner or circumstances of their deaths. Authorities also have not disclosed how long the remains had been buried or released a detailed timeline of the alleged killings.
Flores Semyonov emerged as the principal suspect as investigators determined he was no longer in the United States. Police have not said what country they believe he entered or publicly explained how they confirmed his departure. The U.S. Marshals Service says it is using domestic and international law enforcement partnerships to locate him and return him to Arizona.
The federal fugitive case gives authorities additional tools to pursue Flores Semyonov beyond Arizona. U.S. Marshal Van Bayless has said crossing an international border will not end the search and that the agency intends to use available partnerships to locate him. Authorities have not announced that he has been arrested, detained abroad or located in any particular country.
The U.S. Marshals Service describes Flores Semyonov as 6 feet tall and about 177 pounds, with blue eyes. The agency identifies him as a fugitive wanted for homicide and warns that he should be considered dangerous. Law enforcement has asked members of the public not to try to apprehend him themselves.
The international search follows the release of additional information about the family in the days before the welfare check. According to the newly released police report, relatives told investigators that Flores Semyonov had become increasingly isolated and that his behavior had changed substantially since college. The report references a mental health diagnosis but redacts the condition. Authorities have not identified a mental health condition as a motive or established a causal link between any diagnosis and the deaths.
Hector Flores was an associate professor at California State Polytechnic University, Pomona, where he had worked since 2015. University officials said he taught strategic management and other business courses, conducted research and participated in faculty governance. He had been scheduled to teach during the fall 2026 semester.
Larissa Flores worked in psychiatric care and was affiliated with Circle the City, an organization that provides health services to people experiencing homelessness in the Phoenix area. The organization described her as a valued colleague who cared deeply for patients. The Flores Semyonov family has said relatives are cooperating with investigators and asked for privacy as the case continues.
Flores Semyonov remained listed as a wanted fugitive by the U.S. Marshals Service as of Thursday. No court proceeding involving him can move forward in person unless he is located and returned to authorities, and investigators have not announced his whereabouts. The deaths remain under investigation while the international search continues.
Author note: Last updated August 13, 2026.