Authorities on Tuesday dropped murder charges against one of two brothers who had been accused of killing a couple in rural Washington state and burying their remains in a remote forest clearing.

The Snohomish County Sheriff's Office said further investigation into the April deaths of Monique Patenaude and her husband, Patrick Shunn, established that Tony Clyde Reed was not present when they were killed. Instead, the prosecutor's office charged him with rendering criminal assistance in the first degree.

Reed is the brother of John Blaine Reed, a former neighbor who had feuded with the couple and who remains at large on murder charges in Mexico, authorities believe.

Tony Reed fled with his brother to Mexico, but returned last month and helped detectives locate the couple's remains, in the root well of a wind-toppled fir tree 10 miles up a gravel logging road from Oso, a tiny community northeast of Seattle.

News of the reduced charges for Tony Reed came as detectives arrested the brothers' parents, Clyde Reed, 81, and Faye Reed, 77, at their home in Ellensburg — also for investigation of first-degree rendering criminal assistance.

Investigators said the parents admitted providing the vehicle in which their sons fled the state to make their way toward Mexico; giving them financial assistance; and transferring the title of John Reed's truck, which is believed to have been used in the slayings, to Faye Reed.

James Kirkham, Tony Reed's lawyer, said he would represent the parents at a hearing Wednesday in an effort to get them out of jail, citing their age and that "they have no criminal history and they made the poor choice of helping their son out."

Authorities said they plan to arrest others who also aided the brothers. They've previously indicated that two friends in Phoenix gave them another car and $500, knowing the siblings were on the run.

"We absolutely will arrest anyone who has helped a murderer escape justice," Sheriff Ty Trenary said in a news release.

The couple was reported missing April 12, and suspicion fell on the Reeds in part because a neighbor saw them at the gated driveway they formerly shared with the couple the next day, court documents said. Authorities said surveillance video captured the couple's vehicles being simultaneously driven up a gravel logging road leading to where the bodies were found, indicating that at least two people were involved in covering up the killings.

In interviews with detectives early in the investigation, Clyde Reed "indicated that he did not know where his two sons were, but if he did, he would not tell law enforcement," a deputy prosecutor wrote when the state charged the brothers.

The sheriff's office said John Reed is believed to be in the Tijuana, Rosarita or Ensenada areas of Mexico, where investigators recently distributed wanted posters for him, and that he had been driving a 2002 gold Acura 3.2 TL with Arizona plates BNN-9968. He's described as armed and dangerous, 5-foot-8, 190 pounds with hazel eyes and gray hair.

The U.S. Marshals Service is offering a $5,000 reward for information leading to his capture.