Investigators are looking into whether the deaths of four people in central Washington state this week are tied to an earlier kidnapping and murder case, after authorities identified one of the victims as a potential witness in it.

The Chelan County Sheriff's Office said Thursday it believes Benito Caro Sedano, 56, the suspect in the kidnapping case, shot and killed two people in a vehicle in an orchard on the north shore of Lake Chelan on Tuesday, then fired at a responding deputy and hit the deputy's car at least nine times.

Later in the day, Sedano shot and killed his wife, Maria Sedano, 50, and himself in their home during a standoff with police.

The shootings came the day before Sedano had been due to appear in court for a change of plea hearing on charges related to the earlier kidnapping, assault and robbery.

The victim in the kidnapping case, Ignacio Ramirez, was found dead in a shallow grave near Sedano's home in August 2014. Authorities say Sedano kidnapped Ramirez at gunpoint and was the last person seen with him, but he had not been charged with the killing. Sedano was arrested last December.

Sheriff Brian Burnett said Thursday that he had expected Sedano to plead guilty Wednesday and face a lengthy prison term, and he called the timing of the shootings "more than coincidental." Sedano had been out on $1 million bond pending the plea hearing. Burnett said he didn't immediately know how Sedano had posted the bond.

"Obviously you have to put up some serious cash or collateral. But I don't have any information on that," he said.

The sheriff's office on Thursday released the identities of the two people found dead in the vehicle: Edgar Cisneros-Costumbre, 24, and Jose Luis Leyva Rodriguez, 58. The sheriff said Cisneros had been interviewed by authorities as a potential witness in Ramirez's kidnapping, robbery and murder.

The sheriff's office said the first deputy to respond to the initial shootings Tuesday afternoon saw a man driving nearby on a four-wheel all-terrain vehicle with a passenger in the back. Thinking they might have been witnesses or victims of the shooting, the deputy got out of his cruiser — but the driver of the ATV raised a long gun and started firing, Burnett said.

The deputy got back in his car and started backing away, but one of the bullets hit the left front tire, causing the car to skid, spin and hit an embankment.

The deputy took cover behind the cruiser and called for backup, and the ATV fled. Eleven shell casings were found in the area, the sheriff's office said. The identity of the second person on the ATV is not known.

Burnett said that after police went to Sedano's home adjacent to the orchard Tuesday, they saw a vehicle with four people inside leaving the property. One — identified as Sedano's son, Benny Sedano Jr. — jumped out and ran off. He was located the next day and arrested on an outstanding warrant from the Department of Corrections. He has been questioned about the shootings, but he was not arrested in connection with the shootings, Burnett said.

The investigation continues, he said.