(CNN)Almost 15 months ago, Orrin and Orson West's adoptive parents told police the young boys disappeared from the family's Southern California yard, authorities said.
Now, authorities say the brothers were actually killed by their adoptive parents months before they were reported missing -- though their bodies "have not been found," Kern County District Attorney Cynthia Zimmer said Wednesday.
"This morning, I am saddened to announce that the investigation has revealed that Orrin and Orson West are deceased," Zimmer said.
"The investigation has also revealed that they died three months before their adoptive parents reported them missing. However, I am pleased to announce that this week, the Kern County grand jury indicted Trezell and Jacqueline West -- the adoptive parents -- for the murder of Orrin and Orson West."
Bakersfield police arrested the California City couple around 7 p.m. Tuesday, the district attorney said.
Zimmer said both have been charged with:
- Two counts of second-degree murder, in connection with the deaths of Orrin and Orson West
- Two counts of child abuse, with Orrin and Orson West as the victims
- One count of false report in an emergency
If convicted of both counts of murder, each of the defendants could face 30 years to life in prison, Zimmer said. She told reporters she could not go into specific details of the case.
CNN was not immediately able to determine whether the Wests have legal representation. The couple will be arraigned Thursday, Zimmer said.
The Wests have two other adopted children and two biological children, all of whom are in child protective services custody, Zimmer said.
How the case unfolded
On December 21, 2020, Trezell and Jacqueline West told California City police that Orrin, then 4, and Orson, then 3, had disappeared from the family's backyard, Zimmer said.
Police and volunteers from the community searched, but to no avail, the district attorney said.
In the early days of the search, Trezell and Jacqueline West spoke to reporters and asked for the public's help in finding the boys.
Trezell West said he was moving firewood as his wife wrapped Christmas gifts inside the house and the boys played outside.
"I came to my house, I saw them there, go in the house, I came back out, I didn't see them now," Trezell West said at the time. "I realized that I left the gate open, and I panicked. I came inside the house, searched the house -- me and my wife."
Trezell West said he got in his van to search for the boys. "I looked down the street, both directions. It was getting dark, getting cold." He said when he couldn't find the boys, he came home and told his wife they needed to call the police.
During the December 2020 briefing, a reporter said the boys' biological mother thinks the couple was involved.
"That's understandable, I would think the same thing," Trezell West said. He encouraged the public to call the police with any information.
Several law enforcement agencies "worked diligently -- hundreds of hours in the next 12 months -- looking for the boys," Zimmer said.
The district attorney declined to detail the information that led authorities to believe the adoptive parents killed the two boys in September 2020, about three months before they were reported missing.
"I'm not permitted to go over the facts of the case in this case," Zimmer told reporters Wednesday. "The facts of the case are to be what we produce in the jury trial because we want both the prosecution and the defense to have a fair trial in the case."
But Zimmer noted that the information was enough for a grand jury to indict Trezell and Jacqueline West.
The grand jury convened in December and heard testimony from dozens of witnesses, the district attorney said.
"We were able to prove that to the grand jury that the boys have died, that they were murdered," Zimmer said. "And we did that through a combination of direct and circumstantial evidence. And the grand jury was convinced that they were dead."
The boys' bodies have not been found
Zimmer acknowledged some people may be confused as to how anyone could be charged with murder when no body has been found.
"The fact that law enforcement have not found their bodies does not preclude a murder prosecution," the district attorney said.
She said there have been other "no body" cases have led to murder convictions across the country, including at least two such cases in Kern County.
'Now it's time to start grieving'
Rosanna Wills, the boys' biological cousin, said she was devastated by the news that authorities believe Orrin and Orson are dead.
"Now it's time to start grieving," Wills told CNN affiliate KBAK after the district attorney's announcement.
"We just want to know why would you hurt two babies."
But the boys' aunt, Kiki Hoard, said she can't fully grieve until the boys' bodies are found.
"We're not going to have closure until they bring the babies home so we can have a proper burial," Hoard told KBAK.
"That's all we want now -- their bodies, closure, so we can grieve now."
Local police chiefs acknowledged the work of the officers and volunteers who scoured the community for Orrin and Orson.
"This is a tragedy, an absolute tragedy that was reported in my city that two small boys could be killed by their parents," California City Police Chief Jon Walker said.
Bakersfield Police Chief Greg Terry said "this is not the outcome that we and so many had hoped and prayed for over the last year."
"Our thoughts and prayers go out to the families of Orrin and Orson, who, with news today, their worst fears have been realized," Terry said Wednesday.
But there will be no complete resolution to the case until the bodies are found and "these boys are brought home," Terry said.
"We now realize that the search for the boys began after the real tragedy had already occurred."