Litchfield Park, Arizona — A family tragedy has turned into a murder investigation after an Arizona couple was discovered buried in their own backyard, with authorities accusing their 27-year-old son of killing them after becoming angry over his father’s alleged infidelity.
Police say Hector Flores and Larissa Flores had not been heard from since July 29. Days later, a relative became concerned enough to request a welfare check, leading investigators to a disturbing discovery at the couple’s home.
Relative Requests Welfare Check on Missing Couple
According to a police report, a family member contacted 911 on August 4 after Hector and Larissa stopped answering their phones.
The relative agreed to allow officers inside the Litchfield Park residence but reportedly remained outside because he was concerned about what police might find inside.
Those concerns quickly proved justified. Officers discovered large amounts of blood inside the home, along with indications that someone had attempted to clean up the scene.
As investigators continued searching the property, they eventually made a grim discovery in the backyard.
Couple Found Buried Behind Their Home
Police found Hector Flores and Larissa Flores buried in the backyard of their residence. Their son, Matthew Christopher Flores Semyonov, was not at the home when officers arrived.
Investigators later determined that Semyonov had allegedly fled the country, according to authorities.
The U.S. Marshals Service District of Arizona is now assisting with the search for him. Semyonov is wanted on first-degree murder and other charges, as investigators continue building their case.
Family Says Son Became Increasingly Troubled
According to the police report, relatives described a dramatic change in Semyonov’s behavior before his parents’ deaths.
After finishing college, he reportedly moved back in with his parents and became increasingly isolated, with family members saying his lifestyle and behavior had changed “completely.” A relative also recalled Semyonov making comments that appeared threatening.
One statement he allegedly made was:
“You’ll get what’s coming to you.”
Investigators were also told about unusual behavior involving his mother’s plants. On one occasion, he allegedly told her:
“The plants told me they were thirsty.”
Relatives told police that Semyonov had previously been diagnosed with a mental health condition, although the diagnosis itself does not establish a connection to the killings.
Father’s Alleged Affair May Have Triggered Conflict
Police say investigators learned that Semyonov had discovered that his father was allegedly cheating on his mother.
According to the police report, Semyonov became upset not only about the alleged affair but also because his mother had chosen to remain with his father. Authorities are investigating whether that discovery played a role in the alleged killings.
However, the precise circumstances surrounding the deaths and what happened inside the home remain part of the ongoing investigation.
Son Allegedly Fled the United States
After investigators discovered the bodies, they learned that Semyonov had apparently left the country. Authorities have not publicly disclosed where they believe he went or exactly how they determined he had fled the United States.
The U.S. Marshals Service District of Arizona is leading the search in cooperation with local authorities.
According to the Marshals Service, Semyonov is wanted on a federal charge of unlawful flight to avoid prosecution, in addition to charges filed by the Avondale Police Department. Those state charges include first-degree murder, dangerous domestic violence, and abandonment or concealment of a dead body.
Search Continues for Suspect
As of the latest information available, Semyonov remained wanted by authorities.
The investigation is continuing as law enforcement works to determine the full timeline of the alleged killings, the circumstances surrounding the disposal of the bodies and where the suspect traveled after leaving the country.
The case has left a family searching for answers after a missing-person welfare check uncovered a suspected double homicide.
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