Authorities believe multiple people wanted for questioning in the homicide investigation of three Pasco residents and an unborn baby have left the Umatilla County area.
And investigators with the Benton County Sheriff's Office are working to track where the other persons of interest may be.
Authorities have not identified the people or released how they could be connected to the investigation, said Detective Sgt. Kevin McCary, sheriff's office spokesman.
Detectives are investigating a possible motive in the Aug. 9 shooting deaths of Abigail Torres-Renteria, 23, who was almost nine months pregnant, David Perez-Saucedo, 22, and Victoria Torres, 19, McCary said.
However, officials did not want to discuss what it could be because doing so could jeopardize the investigation, McCary said.
Detectives plan to meet with the victims' families this week to update them on the investigation.
Authorities told the Herald on Monday that Perez-Saucedo knew at least one of the men named as a person of interest in the Aug. 9 shootings.
McCary confirmed that Perez-Saucedo and Francisco Javier Resendiz Miranda both worked together at Grandview-based Wyckoff Farms.
"Most of the people we have interviewed as witnesses and suspects ... were working at Wyckoff Farms," he said.
Miranda and Cristian R. Hurtado, both 23, have been identified by police as persons of interests in the case. The Oregon men, who are at the Umatilla County jail, have not been charged in connection with the homicides.
Miranda, of Umatilla, is being held on suspicion of attempted assault, unlawful use of a weapon and menacing charges stemming from an incident at a Umatilla gas station where he allegedly threatened a man.
The victims were seen leaving Pik-A-Pop in Umatilla late Aug. 8 with a group of people that included Miranda, court documents said. One person in the group was seen on video with a weapon.
Authorities believe the victims were shot just hours later in a rural Benton County cornfield. Their bodies were found by a farm worker early the same morning.
Hurtado, of Irrigon, is being held on unrelated charges of forgery, aggravated theft and identity theft. He was arrested shortly after Miranda.
Detectives have also been in contact with a third Oregon man who may be a person of interest in the case, though he has not yet been arrested, McCary said.
McCary emphasized that just because Miranda and Hurtado are in jail, it doesn't mean that they are suspected of shooting the victims, he said.
"We have contacted a ton of people," McCary said.
Authorities have served about 20 search warrants in Washington and Oregon during the course of the more than two-week investigation.
At least seven vehicles have been searched, including the vehicle the victims were driving the night of shootings, McCary said. Detectives also have gathered phone records and DNA.
Investigators will comb through the evidence and determine what needs to be sent to the Washington State Patrol Crime Lab for analysis.
McCary said the investigation is far from over and detectives are working to bring justice to the victims' families.
"It takes a lot of effort and a lot of work on everybody's part," he said. "We never want to get to a point where we get to trial and find out a mistake has been made."