Malheur County District Attorney David Goldthorpe said the deadly standoff Sunday in Ontario was a domestic violence incident. (The Enterprise/File).

ONTARIO – Police continue to investigate a domestic incident in Ontario that turned deadly on Sunday.

Two deaths came days after police responded to an earlier tip of potential domestic abuse.

Police shot and killed Henry Martinez Jr., 49, after a four-hour standoff with police and after he apparently killed Carlen Mercado, 51. Martinez was listed as being from Nyssa and records show Mercado was from the area of Rialto, California, east of Los Angeles.

Malheur County District Attorney Dave Goldthorpe said in a news release that police responded Sunday to a relative’s call that Mercado was being held against her will at a home at 580 S.E. 13th St.

Officers from the Ontario Police Department and the Malheur County Sheriff’s Office responded at about 12:20 p.m. Sunday where a “hostage situation developed,” according to Goldthorpe’s release.

He said that police negotiators tried to “establish contact with Ms. Mercado to ensure she was alive.”

After four hours of failed negotiations, the Malheur County Special Emergency Response Team deployed a flash bang grenade and chemical gas to convince Martinez to leave the house.

As the SERT team moved into the house through an entryway, Martinez threatened police with the knife as he walked toward them.

At that point two sheriff’s deputies “discharged their weapons,” according to the release.

Martinez was shot “several times” and died at the scene.

Police then found Mercado’s body.

Exactly how Mercado died is still undetermined, though Goldthorpe said it is “a logical conclusion” she was stabbed.

Goldthorpe said to “his knowledge” no other weapons were recovered at the house after the shooting and no one else was in the home at the time.

The Oregon State Police is investigating.

He said Martinez and Mercado had a relationship. Photos on their Facebook pages show the two together over more than two years.

Goldthorpe said Mercado was living in California, but was back in Ontario for an unspecified reason.

“It was something to do with their relationship. Not exactly sure why she was there but she had been there for several days,” said Goldthorpe.

Goldthorpe said police were called to the home “several days prior” to the Sunday incident.

“I believe it was kind of a similar situation as far as another third-party reporting there was a possibility of violence between the two of them. When they responded there was no signs of violence and, once separated, both parties said everything was fine,” said Goldthorpe.

“These cases are terrible and tragic and this was the worse-case scenario,” said Goldthorpe.

Previous coverage:

Special report: Domestic violence is a familiar and persistent crime in Malheur County.

News tip? Contact reporter Pat Caldwell at [email protected]

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