The bodies of three men were found close to the grave of a man killed in Mexico in December.
Riverside County Sheriff Chad Bianco is investigating whether the deaths of three men in Perris, California are linked to cartel violence.
Jaime Covarrubias Espindola, 50, Jose Maria Aguilar-Espejel, 38, and Rodrigo Aguilar-Espejel, 28, were killed.
The trio were found by the grave of Uver Hernandez Castaneda.
The 36-year-old was killed in a suspected cartel hit in December, CBS LA reported.
He was found dead on a Mexican motorway after reportedly being tortured to death.
When asked whether the three men were executed, Sheriff Bianco said: “All three were killed at the same time there. You can get into semantics of what you would call it, but it certainly seems that way.”
He added: “I mean, three people killed at the same time, that was a message for something, whether it was for someone else, or whether it was to them."
Police officers are examining security cameras to see how the men got to the graveyard.
Sheriff Bianco said law enforcement was in touch with Mexican authorities.
Photos of the scene taken by CBS LA show the three victims lying on the ground of the cemetery surrounded by flowers and Valentine's Day balloons.
In a statement Perris Mayor Michael Vargas said: "I have been in touch with local law enforcement officials and will continue to monitor developments.
"We are committed to seeing those responsible for these horrific acts brought to justice."
