(DENVER) — An Idaho man who recently ran for governor has been arrested for the 1984 murder of a 12-year-old girl, prosecutors said.

Steven Pankey is accused of kidnapping Jonelle Matthews from her Greeley, Colorado, home on the night of Dec. 20, 1984, and then shooting her in the head, according to the indictment.

Pankey lived about 2 miles from Matthews’ home at the time, the indictment said.

Matthews was missing for decades. Her remains were found in Greeley in July 2019, according to Denver ABC affiliate KMGH.

Pankey, 69, is charged with first-degree murder after deliberation, first-degree felony murder, second-degree kidnapping, and crime of violence, the Weld County District Attorney’s office said.

Pankey ran as a Republican in Idaho’s 2018 gubernatorial primary, KMGH reported. He also ran as a Constitutional Party candidate in 2014, KMGH said.

According to the indictment, Pankey sent an “alibi” letter to police in 2013 that authorities allege contained “false statements and superfluous details” in his explanation of plans for a family trip to California starting on Dec. 21 — the morning after Matthews disappeared.

Pankey’s ex-wife, Angela Hicks, said the family trip was unexpected and began on Dec. 22, the indictment said. On the drive home Pankey allegedly “uncharacteristically listened to the radio, searching for news accounts of Jonelle’s disappearance,” the indictment said.

Pankey allegedly “forced” Hicks “to read the newspaper accounts about Jonelle to him,” the indictment said.

When they got home, Pankey allegedly started digging in their yard, and about two days later, one of their cars burst into flames, Hicks said, according to the indictment.

Pankey “intentionally inserted himself in the investigation many times over the years claiming to have knowledge of the crime which grew inconsistent and incriminating over time,” the indictment said.

According to the indictment, Pankey “knew of, and discussed, a crucial piece of evidence” that was withheld from the public — that a rake was used to cover up footprints in the snow.

He also “repeatedly demanded immunity in exchange for information he claimed to possess about the murder,” according to the indictment.

“In a 1999 pleading filed with the Idaho Supreme Court, Steven Dana Pankey argued if the Court ruled in certain fashion, ‘it is reasonable for the appellant to believe he would get the death penalty for revealing the location of Jonelle Matthews’ body,"” the indictment said.

Pankey had searched for information about Matthews online, but after detectives contacted him last year, Pankey tried to delete his search history, prosecutors said.

Pankey was arrested on Monday at his home in Idaho and is in custody at Idaho’s Ada County Jail, authorities said. A court date in Colorado hasn’t been set, said prosecutors.

There’s no “definitive DNA link” between Pankey and Matthews, Weld County District Attorney Michael Rourke said at a new conference.

According to Denver station KUSA, Pankey’s attorney, Anthony Viorst, said Tuesday, “The fact that they waited 36 years to indict him reflects the fact they don’t have any evidence, there’s never been any evidence. I anticipate he will be exonerated of all charges.”

Viorst could not immediately be reached by ABC News for comment.

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