The remains of two people were found in an Arizona backyard Thursday as police searched for a missing father and mother whose son is believed to have fled the country, police said.

The son, Matthew Flores, 27, was initially part of the missing persons report made by concerned family members Tuesday, Avondale police spokesperson Officer Daniel Benavidez said.

When police went to conduct a welfare check at the home in Litchfield Park they saw evidence of foul play, he said.

They identified “a large amount of blood, and we also identified what we believed as evidence in an attempt to conceal that blood, and that’s what made us believe that foul play is involved,” Benavidez said at a news conference Thursday.

The human remains found in the backyard had not been identified Thursday afternoon, police said. They were being recovered with the assistance of Phoenix police homicide unit when Benavidez spoke with reporters.

Family members on Tuesday afternoon called police and said they expected the mother, father and their adult son to be at the residence where the remains were later found, Benavidez said.

Police did not release the names of the parents Thursday on request from the family that reported the people missing, Benavidez said.

The bodies were in a state of decomposition, Benavidez said. He did not say how long they were believed to have been in the backyard.

Police were calling Flores a suspect in the missing persons investigation Thursday, Benavidez said.

Police were looking for Flores and have leads in the case, Benavidez said. They asked anyone with information about Flores’ movements or about him to contact the department.

Benavidez did not say to which country Flores is believed to have fled. “All I can say is that he fled the country,” he said.