U.S. Marshals Lead International Search for Arizona Man Suspected in Parents’ Deaths

Phoenix, AZ - The U.S. Marshals Service District of Arizona is leading an international fugitive investigation to locate a 27-year-old man suspected in the deaths of his parents after human remains were discovered buried in the backyard of the family’s Litchfield Park residence.

On August 7, 2026, the Avondale Police Department formally requested assistance from the District of Arizona’s U.S. Marshals-led WANTED Violent Offender Task Force in locating and apprehending Matthew Christopher Flores Semyonov.

Investigators believe Flores Semyonov fled the United States. At the request of the Avondale Police Department to lead the fugitive hunt, the U.S. Marshals Service obtained a federal arrest warrant from the U.S. District Court for the District of Arizona charging Flores Semyonov with Unlawful Flight to Avoid Prosecution.

“The U.S. Marshals Service will use every available resource, including our domestic and international law enforcement partnerships, to locate Flores Semyonov and return him to Arizona to face justice,” said United States Marshal Van Bayless. “Crossing international borders will not prevent us from pursuing those accused of committing violent crimes. We will remain steadfast in this search and in our commitment to securing justice for the victims and their family.”

The investigation began after family members requested a welfare check on Flores Semyonov and his parents. Avondale police officers searched the family’s residence but did not locate any of the three individuals. During the search, investigators discovered a significant amount of blood and evidence indicating an attempt had been made to clean the residence.

A subsequent search of the property led investigators to discover human remains buried in the backyard. Positive identification of the remains is pending.

The U.S. Marshals Service is leading the fugitive investigation into Flores Semyonov’s whereabouts and is coordinating efforts to locate and apprehend him. The Avondale Police Department remains the lead agency responsible for the criminal investigation into the disappearance and suspected deaths of Flores Semyonov’s parents and is working closely with federal law enforcement partners to advance their investigation.

The U.S. Marshals Service is coordinating with federal and international law enforcement partners to locate and apprehend Flores Semyonov. Anyone with information regarding Flores Semyonov’s whereabouts is urged to contact the U.S. Marshals at 1-877-WANTED-2 or send tip information to usmstips@usdoj.gov. 

Flores Semyonov should be considered dangerous. Members of the public should not approach or attempt to apprehend him and should immediately contact law enforcement if he is seen.

The Arizona WANTED Violent Offender Task Force is a U.S. Marshals Service led multi-jurisdictional fugitive apprehension unit responsible for more than 1748 arrests in the last year. The task force is comprised of 22 agencies bringing together the resources of federal, state and local law enforcement agencies to locate and arrest the community’s most violent offenders and sexual predators.