Police have launched an international manhunt for a missing man after two bodies were found buried in the backyard of a home in Lichfield Park, Arizona.

Officers made the grim discovery after relatives of the couple living at the property requested a welfare check on them and their adult son Tuesday.

The house proved to be empty but Avondale Police Officer Daniel Benavidez said colleagues discovered “a large amount of blood, and evidence to us that there was an attempt to conceal that.”

A missing person’s investigation was commenced in response to the “suspicious circumstances” of the trio’s disappearance, with the Avondale Police Department notifying local residents via a Facebook video message in which it appealed for information but said there was no threat posted to the wider community.

Arizona Family reports that investigators were seen removing bags of evidence from the house Wednesday evening and searching through containers stored in its garage.

The bodies were then discovered Thursday, with Benavidez telling local media he could not say how long they had been there but that they were “in a state of decomposition.”

Drone footage recorded at the scene showed investigators erecting tents and digging with shovels and an excavator, according to Arizona Family, which said that a neighbor had told it the swimming pool next to the spot where the bodies were found had only been installed last month.

The APD has not named the victims at the request of the family but has said it is working with homicide detectives from Phoenix to recover the remains and seeking the son of the couple who lived at the property, Matthew Flores, 27, who is believed to have fled abroad.

“I can’t speak to why he fled the country,” Benavidez said. “What I can say is that we believe him to be a suspect in this missing persons investigation.”

He specified that Flores was not considered a suspect in the homicide investigation at present, only in the missing persons case, but declined to say whether he had a criminal record or prior history of mental illness.

Neighbors told Arizona Family they were shocked by the episode occurring in such a quiet area, although some claimed to have seen a suspicious vehicle circling at the time of the accident and one person said they had heard yelling from the house Monday, prior to the welfare check.

“This is not the neighborhood you would think something like this would happen, you know, that they’d be buried in the backyard,” resident JoAnne Nix said.

Another local, who declined to be named, told the outlet: “We don’t really have much going on here. I don’t even really see my neighbors for the most part.

“I don’t really see them come home. I don’t see them leave. It’s a super, super quiet neighborhood. So this is a shock to all of us. We’re all just trying to figure out what the heck is going on. And hopefully everything is good and I hope everyone’s OK.”

That person claimed to have heard someone shout, “Please stop,” at the property Monday as she walked by. “But I was like, ‘OK, we live by a middle school; it might be nothing,’ so I didn’t think more of it,” she said.

Another neighbor, Alec Rogers, told Fox 10: “The dad there, we see him every once in a while, he’s very, very friendly but we don’t talk too much just whenever we see him, we say hello.”

Rogers said that he too had heard raised voices, although on Tuesday morning, not Monday: “There was a little bit of yelling and I don’t know exactly who from.”

Officers have asked anyone with information on Matthew Flores’s whereabouts to call the APD on 623-333-7001.